SHIRE PHARMACEUTICALS GROUP PLC
F-4, 1999-11-15
PHARMACEUTICAL PREPARATIONS
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<PAGE>

   As filed with the Securities and Exchange Commission on November 15, 1999
                                                  Registration No. 333-

- --------------------------------------------------------------------------------
- --------------------------------------------------------------------------------
                                 UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION
                             Washington D.C. 20549

                                    FORM F-4
                             REGISTRATION STATEMENT
                                     UNDER
                           THE SECURITIES ACT OF 1933

                        SHIRE PHARMACEUTICALS GROUP plc
             (Exact name of Registrant as specified in its charter)
         England and Wales            2834              Not Applicable
  (State or other jurisdiction of
   incorporation or organization)
            (Primary Standard Industrial Classification Code Number)
                                               (I.R.S. Employer Identification
                                                             No.)
             East Anton                          William A. Nuerge
              Andover                           Shire Richwood Inc.
         Hampshire SP10 5RG                   7900 Tanners Gate Drive
              ENGLAND                        Florence, Kentucky 41042
         (44)1-264-333-455                        (606) 282-2100
 (Address, including zip code, and    (Name, address, including zip code, and
         telephone number,                       telephone number,
      including area code, of       including area code, of agent for service)
  Registrant's principal executive
              offices)
                                   Copies to:
       John P. Mitchell, Esq.                 Lawrence Lederman, Esq.
      Cahill Gordon & Reindel           Milbank, Tweed, Hadley & McCloy LLP
           80 Pine Street                     1 Chase Manhattan Plaza
      New York, New York 10005               New York, New York 10005
           (212) 701-3000                         (212) 530-5000

  Approximate date of commencement of proposed sale to public: As promptly as
practicable after this Registration Statement becomes effective and the
conditions to consummation of the merger described herein have been satisfied
or waived.
  If this Form is filed to register additional securities for an offering
pursuant to Rule 462(b) under the Securities Act, check the following box and
list the Securities Act registration statement number of the earlier effective
registration statement for the same offering. [_]
  If this Form is a post-effective amendment filed pursuant to Rule 462(d)
under the Securities Act, check the following box and list the Securities Act
registration statement number of the earlier effective registration statement
for the same offering. [_]
                        CALCULATION OF REGISTRATION FEE
<TABLE>
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- -------------------------------------------------------------------------------------------------------
<CAPTION>
                                                         Proposed          Proposed
                                        Amount            maximum           maximum          Amount of
     Title of each class of              to be        offering price       aggregate       registration
   securities to be registered       registered(2)       per share     offering price(3)      fee (4)
- -------------------------------------------------------------------------------------------------------
<S>                                <C>               <C>               <C>               <C>
Ordinary shares, nominal
 value 5p each(1)................     45,060,330      Not applicable   $1,157,130,403.63    $321,682.25
- -------------------------------------------------------------------------------------------------------
- -------------------------------------------------------------------------------------------------------
</TABLE>
(1) American Depositary Shares ("Shire ADSs"), evidenced by American Depositary
    Receipts, issuable upon deposit of ordinary shares, nominal value 5p each,
    of Shire Pharmaceuticals Group plc ("Shire") will be registered on a
    separate registration statement on Form F-6. Each Shire ADS represents
    three ordinary shares.
(2) Based on the product of (i) 35,197,883, the maximum number of shares of
    common stock, $.01 par value per share ("Roberts Common Stock"), of Roberts
    Pharmaceutical Corporation ("Roberts") that would be outstanding
    immediately prior to the merger of Roberts and a subsidiary of Shire,
    assuming the exercise of all underlying Roberts options (whether or not
    currently exercisable), and (ii) a conversion ratio of 1.2802 ordinary
    shares for each share of Roberts Common Stock.
(3) Estimated solely for the purpose of calculating the registration fee
    required by Section 6(b) of the Securities Act of 1933, and computed
    pursuant to Rules 457(f)(1) and 457(c) thereunder based on $32.875, the
    average of the high and low sale prices of shares of Roberts Common Stock
    on November 9, 1999 as reported on the American Stock Exchange, and
    35,197,883, the maximum number of shares of Roberts Common Stock to be
    exchanged in the merger.
(4) In accordance with Rule 457(b) of the Securities Act of 1933, the amount of
    the registration fee includes $185,228.86, which is the amount paid to the
    Securities and Exchange Commission on September 3, 1999 in connection with
    the confidential filing of the preliminary Prospectus-Proxy Statement
    included as part of this registration statement.

  The Registrant hereby amends this Registration Statement on such date or
dates as may be necessary to delay its effective date until the Registrant
shall file a further amendment which specifically states that this Registration
Statement shall thereafter become effective in accordance with Section 8(a) of
the Securities Act of 1933 or until the Registration Statement shall become
effective on such date as the Commission, acting pursuant to said Section 8(a),
may determine.
- --------------------------------------------------------------------------------
- --------------------------------------------------------------------------------
<PAGE>


                       ROBERTS PHARMACEUTICAL CORPORATION
                               Meridian Center II
                             4 Industrial Way West
                          Eatontown, New Jersey 07724

                               ----------------

                   NOTICE OF SPECIAL MEETING OF SHAREHOLDERS
                         TO BE HELD ON          , 1999

                               ----------------

To the Shareholders of
Roberts Pharmaceutical Corporation:

   A special meeting of shareholders of Roberts Pharmaceutical Corporation will
be held on        , 1999, at our offices at Meridian Center II, 4 Industrial
Way West, Eatontown, New Jersey 07724, at 10:00 a.m., local time, for the
following purposes:

  .  To consider and vote on a proposal to approve an agreement and plan of
     merger among Roberts, Shire Pharmaceuticals Group plc and Ruby
     Acquisition Sub Inc., a newly formed subsidiary of Shire. In the merger
     Ruby Acquisition Sub will be merged with and into Roberts, with Roberts
     continuing as a subsidiary of Shire; and

  .  To consider and vote on such other matters as may properly be presented
     incident to the conduct of the special meeting.

   The accompanying Prospectus-Proxy Statement contains information regarding
the business to be considered at the special meeting. A copy of the merger
agreement is attached as Annex A to the Prospectus-Proxy Statement.

   The board of directors of Roberts by a unanimous vote has determined that
the merger agreement and the transactions contemplated by the merger agreement,
including the merger, are in the best interests of Roberts and its
shareholders, and has adopted the merger agreement. The board of directors of
Roberts recommends that you vote in favor of the proposal to approve the merger
agreement.

   Holders of Roberts common stock of record at the close of business on
October 27, 1999, the record date established by the board of directors of
Roberts in connection with the special meeting, are entitled to notice of, and
to vote at, the special meeting. Under New Jersey law, holders of Roberts
common stock are not entitled to dissenters' rights in connection with the
merger.

   YOU ARE CORDIALLY INVITED TO ATTEND THE SPECIAL MEETING. TO ENSURE YOUR
REPRESENTATION AT THE MEETING, HOWEVER, YOU ARE URGED TO SIGN AND DATE THE
ACCOMPANYING PROXY AND MAIL IT AT ONCE IN THE ENCLOSED ENVELOPE. PROMPT
RESPONSE IS HELPFUL AND YOUR COOPERATION WILL BE APPRECIATED.

                                          By Order of the Board of Directors,

                                          Anthony A. Rascio
                                          Vice President and Secretary

Eatontown, New Jersey
    , 1999
<PAGE>

                 Subject to Completion. Dated November  , 1999.

      Shire Pharmaceuticals Group plc  Roberts Pharmaceutical Corporation

   This Prospectus-Proxy Statement is being furnished in connection with the
solicitation of proxies by the board of directors of Roberts Pharmaceutical
Corporation, a New Jersey corporation, for use at a special meeting.

   Roberts' board of directors has unanimously approved a merger agreement
between Roberts and Shire Pharmaceuticals Group plc. At the special meeting,
the Roberts shareholders will be asked to consider and vote on a proposal to
approve and adopt the merger agreement. Each share of Roberts common stock will
be converted into the right to receive between approximately 1.0427 and
approximately 1.2802 American depositary shares of Shire or between 3.1280 and
3.8407 ordinary shares of Shire. You will receive American depositary shares
unless you elect to receive ordinary shares. Each American depositary share
represents three Shire ordinary shares.

   Roberts common stock is listed and traded on the American Stock Exchange
under the symbol "RPC." The Shire ordinary shares are listed and traded on the
London Stock Exchange Limited under the symbol "SHP.L." The Shire American
depositary shares are listed and traded on the Nasdaq National Market under the
symbol "SHPGY." On July 23, 1999, the last business day before public
announcement of the merger agreement, the last reported per share price of
Roberts common stock on the American Stock Exchange, the closing middle market
quotation for the ordinary shares on the Daily Official List of the London
Stock Exchange and the last reported per share price of the American depositary
shares as reported on the Nasdaq National Market were $25.00, 565p and $27.00,
respectively, and on     , 1999, such per share prices were $   ,    p and
$   , respectively.

   Roberts shareholders are urged to read and carefully consider the
information contained in this Prospectus-Proxy Statement. Any shareholder of
Roberts who gives a proxy may revoke it at any time prior to its use.

   See "Risk Factors" beginning on page 31 of this Prospectus-Proxy Statement
for a discussion of certain matters Roberts shareholders should consider before
voting for or against the approval and adoption of the merger agreement.

   Neither the Securities and Exchange Commission nor any state securities
commission has approved or disapproved of these securities or passed upon the
adequacy or accuracy of this Prospectus-Proxy Statement. Any representation to
the contrary is a criminal offense.

   The date of this Prospectus-Proxy Statement is     , 1999 and it is first
being mailed to shareholders on or about this date.
<PAGE>

                               TABLE OF CONTENTS

<TABLE>
<CAPTION>
                                                                           Page
                                                                           ----
<S>                                                                        <C>
ENFORCEABILITY OF CIVIL LIABILITIES UNDER UNITED STATES FEDERAL
 SECURITIES LAWS.........................................................    1
INCORPORATION OF CERTAIN INFORMATION BY REFERENCE........................    1
QUESTIONS AND ANSWERS ABOUT THE SHIRE/ROBERTS MERGER.....................    2
SUMMARY..................................................................    4
General..................................................................    4
The Companies............................................................    4
The Special Meeting......................................................    5
  Record Date; Shares Entitled to Vote...................................    5
  Required Vote..........................................................    5
  Revocability of Proxies................................................    5
The Merger and the Merger Agreement......................................    5
  What You Will Receive in the Merger....................................    5
  Benefits of the Merger.................................................    7
  Recommendation of the Roberts Board of Directors.......................    7
  Roberts' Reasons for the Merger........................................    7
  Opinion of Roberts' Financial Advisor..................................    8
  Interests in the Merger of Persons Affiliated with Roberts.............    8
  Anticipated Accounting Treatment.......................................    8
  Certain U.S. Federal Income Tax Consequences...........................    9
  Dissenters' Rights.....................................................    9
  Conditions to the Merger...............................................    9
  Effective Time of the Merger...........................................    9
  Termination of the Merger Agreement....................................    9
  The Option Agreement...................................................   10
  Governmental and Regulatory Matters....................................   10
  Comparative Rights of Shareholders.....................................   11
Adoption of U.S. GAAP for Reporting Purposes.............................   11
Summary Historical Consolidated Financial Data of Shire..................   15
Summary Historical Consolidated Financial Data of Roberts................   17
Summary Unaudited Pro Forma Combined Financial Data......................   19
Unaudited Pro Forma Combined Condensed Income Statement Nine Months Ended
 September 30, 1999......................................................   20
Unaudited Pro Forma Combined Condensed Income Statement Year Ended
 December 31, 1998.......................................................   21
Unaudited Pro Forma Combined Condensed Income Statement Six Months Ended
 December 31, 1997.......................................................   22
Unaudited Pro Forma Combined Condensed Income Statement Year Ended June
 30, 1997................................................................   23
Unaudited Pro Forma Combined Condensed Income Statement Year Ended June
 30, 1996................................................................   24
Unaudited Pro Forma Combined Condensed Balance Sheet As of September 30,
 1999....................................................................   25
  Notes..................................................................   26
</TABLE>


                                       i
<PAGE>

<TABLE>
<CAPTION>
                                                                           Page
                                                                           ----
<S>                                                                        <C>
Comparative Per Share Data................................................  28
  Notes...................................................................  29
Comparative Market Price Information......................................  30
Dividend Policy...........................................................  30
RISK FACTORS..............................................................  31
  The following are risks that relate to the merger.......................  31
  The following are risks that relate to the operations of both Roberts
   and Shire..............................................................  32
  The following are risks that relate to Shire and will relate to the com-
   bined company
   after the merger.......................................................  38
WHERE YOU CAN FIND MORE INFORMATION.......................................  40
CURRENCIES AND EXCHANGE RATES.............................................  41
SHIRE AFTER THE MERGER....................................................  42
  Overview................................................................  42
  Strategy and Approach...................................................  42
  Sales and Marketing.....................................................  43
  Combined Marketed Products..............................................  43
  Products Under Development..............................................  43
  Drug Delivery Technologies..............................................  44
THE SPECIAL MEETING.......................................................  45
  Date, Time, Place and Purpose...........................................  45
  Matters to Be Considered at the Special Meeting.........................  45
  Record Date; Voting Rights; Voting at the Meeting.......................  45
  Voting of Proxies.......................................................  45
THE MERGER................................................................  47
  Background of the Merger................................................  47
  Roberts' Reasons for the Merger; Recommendation of the Roberts Board of
   Directors..............................................................  49
  Shire's Reasons for the Merger..........................................  51
  Opinion of Financial Advisor to Roberts.................................  52
  Interests in the Merger of Persons Affiliated with Roberts..............  60
  Dissenters' Rights......................................................  62
  Other Effects of the Merger.............................................  62
  Governmental Regulation.................................................  63
  Anticipated Accounting Treatment and Effects............................  63
DESCRIPTION OF INDEBTEDNESS...............................................  64
THE MERGER AGREEMENT......................................................  65
  General; Effective Time and Effects of the Merger.......................  65
  Directors of Shire Immediately Following the Merger.....................  65
  Conversion of Roberts Shares............................................  65
  The Exchange Ratio......................................................  67
  Average Closing Price, Exchange Ratio and Equivalent Value..............  67
  No Fractional ADSs or Ordinary Shares...................................  68
  Exchange of Share Certificates..........................................  68
  Treatment of Roberts Stock Options......................................  68
  Employee Benefits and Options...........................................  69
  Indemnification and Insurance...........................................  69
  Representations and Warranties..........................................  69
</TABLE>

                                       ii
<PAGE>

<TABLE>
<CAPTION>
                                                                           Page
                                                                           ----
<S>                                                                        <C>
  Conduct of Business Pending Merger......................................  69
  No Solicitation.........................................................  70
  Conditions to Consummation of the Merger................................  70
  Termination; Effect of Termination......................................  72
  Amendment...............................................................  74
  Waivers.................................................................  74
THE SHAREHOLDER AGREEMENTS................................................  75
  Shire Shareholder Agreements............................................  75
  Roberts Shareholder Agreements..........................................  75
THE OPTION AGREEMENT......................................................  75
  General.................................................................  75
  Notice of Exercise......................................................  76
  Limitation on Total Profit..............................................  76
MATERIAL TAX CONSEQUENCES.................................................  78
  General.................................................................  78
  United States Tax Consequences of the Merger to U.S. Persons That Bene-
   ficially Own
   Shares of Roberts Common Stock.........................................  79
  United States Tax Consequences of the Ownership of Ordinary Shares and
   ADSs to U.S.
   Persons that Beneficially Own Shares of Roberts Common Stock...........  80
  United Kingdom Tax Consequences of the Ownership of Ordinary Shares and
   ADSs to U.S.
   Persons That Beneficially Own Shares of Roberts Common Stock...........  81
DESCRIPTION OF SHIRE SHARE CAPITAL........................................  84
  General.................................................................  84
  Share Capital...........................................................  84
  Dividends...............................................................  85
  Rights in a Winding-Up..................................................  85
  Shareholder Meetings....................................................  86
  Voting Rights...........................................................  86
  Authorization to Issue Shares; Preemptive Rights........................  87
  Variation of Rights.....................................................  87
  Alteration of Capital...................................................  87
  Disclosure of Interests.................................................  88
  Share Acquisitions......................................................  89
  Transfer of Shares......................................................  89
  Other Shares Information................................................  90
DESCRIPTION OF AMERICAN DEPOSITARY SHARES AND AMERICAN
 DEPOSITARY RECEIPTS......................................................  91
  American Depositary Shares and American Depositary Receipts.............  91
  Share Dividends and Other Distributions.................................  91
  Deposit, Withdrawal and Cancellation....................................  92
  Voting Rights...........................................................  93
  Fees and Expenses.......................................................  93
  Payment of Taxes........................................................  94
  Reclassifications, Recapitalizations and Mergers........................  94
  Amendment and Termination...............................................  94
  Limitations on Obligations and Liability to ADR Holders.................  95
  Requirements for Depositary Actions.....................................  95
  Pre-release of ADSs.....................................................  96
  The Depositary..........................................................  96
</TABLE>

                                      iii
<PAGE>

<TABLE>
<CAPTION>
                                                                            Page
                                                                            ----
<S>                                                                         <C>
COMPARATIVE RIGHTS OF ROBERTS SHAREHOLDERS AND SHIRE SHAREHOLDERS..........  97
  Authorized Capital Stock.................................................  97
  Shareholder Voting Rights................................................  97
  Special Meetings of Shareholders.........................................  97
  Consent of Shareholders in Lieu of Meeting...............................  98
  Rights of Inspection.....................................................  98
  Amendment of Governing Instruments.......................................  99
  Certain Provisions Relating to Share Acquisition.........................  99
  Shareholder Rights Plan.................................................. 100
  Dissenters' Rights....................................................... 100
  Disclosure of Interests.................................................. 100
  Sources and Payment of Dividends......................................... 101
  Classification of the Board of Directors................................. 101
  Removal of Directors..................................................... 102
  Vacancies on the Board of Directors...................................... 102
  Shareholders' Suits...................................................... 103
  Indemnification; Liability of Directors.................................. 103
  Preemptive Rights........................................................ 103
  Rights of Purchase and Redemption........................................ 104
CERTAIN LEGAL MATTERS...................................................... 105
EXPERTS.................................................................... 105
Annex A--Agreement and Plan of Merger .....................................
Annex B--Opinion of PaineWebber Incorporated ..............................
Annex C--Opinion of Bear, Stearns & Co. Inc. ..............................
</TABLE>

                                       iv
<PAGE>

                      ENFORCEABILITY OF CIVIL LIABILITIES
                  UNDER UNITED STATES FEDERAL SECURITIES LAWS

   Shire Pharmaceuticals Group plc is a public limited company incorporated
under the laws of England and Wales. Some of Shire's directors, officers and
controlling persons, as well as certain of the experts named in this
Prospectus-Proxy Statement, reside outside the United States of America and all
or a substantial portion of their assets and the assets of Shire are located
outside the U.S. As a result, with the exception of Shire, it may be difficult
for you to effect service of process within the U.S. upon these persons or to
enforce judgments of courts of the U.S. against them based on civil liabilities
under the U.S. federal securities laws.

               INCORPORATION OF CERTAIN INFORMATION BY REFERENCE

   The SEC allows this Prospectus-Proxy Statement to incorporate by reference
important business and financial information which is not presented in this
document or delivered with this document. Documents relating to this
information for Roberts, excluding exhibits to those documents, unless they are
specifically incorporated by reference in this document, are available without
charge upon request to the Company Secretary, Roberts Pharmaceutical
Corporation, Meridian Center II, 4 Industrial Way West, Eatontown, New Jersey
07724. Telephone requests may be directed to (732) 676-1200. Documents relating
to this information for Shire, excluding exhibits to those documents unless
they are specifically incorporated by reference in this document, are available
without charge upon request to the Company Secretary, Shire Pharmaceuticals
Group plc, East Anton, Andover, Hampshire SP10 5RG, England. Telephone requests
may be directed to (44) 1-264-333-455. To ensure timely delivery of documents,
please make your request no later than [    ], 1999.

   The following documents filed with the SEC by Roberts (File No. 1-10432) are
incorporated in this document by reference: (a) Roberts' Annual Report on Form
10-K for the year ending December 31, 1998; (b) Roberts' Quarterly Reports on
Form 10-Q for the quarterly periods ended March 31, 1999, June 30, 1999 and
September 30, 1999; (c) Roberts' Current Reports on Form 8-K, filed on January
19, 1999, February 2, 1999, February 9, 1999, March 10, 1999, March 18, 1999,
May 6, 1999, May 12, 1999, June 3, 1999, June 10, 1999, July 27, 1999,
September 9, 1999, and October 29, 1999; and (d) Roberts' proxy statement for
its 1999 annual meeting of shareholders.

   The following documents filed with the SEC by Shire (File No. 0-29630) are
incorporated in this document by reference: (a) Shire's Annual Report on Form
20-F for the year ended December 31, 1998 and (b) Shire's Reports on Form 6-K,
filed on January 8, 1999, March 12, 1999, March 23, 1999, April 9, 1999,
May 12, 1999, May 17, 1999, July 6, 1999, July 27, 1999, August 30, 1999,
October 12, 1999, October 22, 1999, October 26, 1999 and October 28, 1999. This
Prospectus-Proxy Statement is accompanied by a copy of Shire's Annual Report.

   Any future filings by either Roberts or Shire under Section 13(a), 13(c), 14
or 15(d) of the Exchange Act subsequent to the date of this Prospectus-Proxy
Statement and prior to the date of the special meeting are also incorporated in
this document by reference. Any of these filings will automatically update and
replace the information that appears or is incorporated in this Prospectus-
Proxy Statement.

   No person is authorized to give any information or to make any
representations not contained in this Prospectus-Proxy Statement or in the
documents incorporated in this document by reference in connection with the
solicitation and the offering made by this document. If given or made, such
information or representation should not be relied upon as having been
authorized by Roberts or Shire. This Prospectus-Proxy Statement does not
constitute an offer to sell, or a solicitation of an offer to purchase, the
securities offered by this Prospectus-Proxy Statement, or the solicitation of a
proxy from any person, in any jurisdiction in which it is unlawful to make this
offer, solicitation of an offer or proxy solicitation. Neither the delivery of
this Prospectus-Proxy Statement nor any distribution of the securities made
under this Prospectus-Proxy Statement will, under any circumstances, create an
implication that there has been no change in the affairs of Roberts or Shire
since the date of this Prospectus-Proxy Statement other than any change
contained in the documents incorporated in this document by reference.
<PAGE>


              QUESTIONS AND ANSWERS ABOUT THE SHIRE/ROBERTS MERGER

Q. When do you expect the merger to be completed?

A. Roberts and Shire hope to complete the merger by [  ], 1999. For a
   description of the conditions to completing the merger, see "The Merger
   Agreement--Conditions to Consummation of the Merger."

Q. What is a Shire ADS?

A. An ADS (which stands for American depositary share) of Shire is a security
   created to allow shareholders to more easily hold and trade interests in
   Shire in the U.S. Shire is an English company which issues ordinary shares,
   equivalent in many respects to common stock in a U.S. company. Each ADS
   represents three ordinary shares. Otherwise, the ADSs are not practically
   different from ordinary shares and carry practically the same rights.
   However, only the ADSs will be traded on the NASDAQ National Market. The
   ordinary shares are traded on the London Stock Exchange and are quoted in
   pounds sterling.
  In the merger, unless you decide otherwise, you will receive ADSs. You will
  be given an opportunity to make your decision at the time you surrender
  your stock certificates. You will be able to withdraw the ordinary shares
  underlying your ADSs whenever you want, if you pay a fee to the financial
  institution which acts as a depositary for the ADSs. The fee is currently
  set at $5 for each 100 or fewer ADSs you convert. For a more detailed
  description of the ADSs, see "Description of American Depositary Receipts."
  For a comparison of the ordinary shares to your current Roberts shares, see
  "Comparative Rights of Roberts Shareholders and Shire Shareholders."

Q. If I am not going to attend the special meeting in person, should I return
   my proxy instead?

A. Yes. After carefully reading and considering the information contained in
   this Prospectus-Proxy Statement, please fill out and sign your proxy. Then
   return it to Roberts in the enclosed return envelope as soon as possible so
   that your Roberts shares may be represented at the special meeting.

Q. What if I plan to attend the special meeting in person?

A. You may request a ticket for admission to the special meeting by marking the
   appropriate box on the proxy enclosed with this Prospectus-Proxy Statement
   and returning it no later than [  ], 1999. If you hold Roberts shares
   through a third party, such as a broker, you should send an account
   statement or similar documentation of ownership to [  ] requesting a ticket.

Q. If my shares are held in "street name" by my broker, will my broker vote my
   shares for me?

A. No. Your broker will not be able to vote your Roberts shares without
   instructions from you. You should instruct your broker how to vote your
   Roberts shares, following the directions provided by your broker. If you do
   not instruct your broker how to vote, your Roberts shares will not be voted
   for or against the merger.

Q. Should I send in my stock certificates now?

A. No. After the merger is completed, we will send you written instructions for
   exchanging your stock certificates. These instructions will also allow you
   to elect to receive ordinary shares instead of ADSs.

Q. What do I need to do now?

A. Just indicate on your proxy how you want to vote and mail your signed and
   dated proxy in the enclosed return envelope as soon as possible so that your
   Roberts shares may be represented at the special meeting.

                                       2
<PAGE>

                         Who Can Help Answer Questions?

        If you have more questions about the merger, you should contact:

                        Dr. Stuart Z. Levine
                        Vice President -- Corporate Communications
                        Roberts Pharmaceutical Corporation
                        Meridian Center II
                        4 Industrial Way West
                        Eatontown, New Jersey 07724
                        (732) 676-1200

                                       3
<PAGE>


                                    SUMMARY

   The following is a summary of certain information contained in this
Prospectus-Proxy Statement which highlights the key aspects of the merger. To
understand the merger more fully and for a more complete description of the
legal terms of the merger, you are urged to read and consider carefully all of
the information contained or incorporated by reference in this Prospectus-Proxy
Statement and in the annexes attached to this Prospectus-Proxy Statement.

General

   This Prospectus-Proxy Statement relates to the proposed merger of Ruby
Acquisition Sub with and into Roberts under the merger agreement, a copy of
which is attached as Annex A to this Prospectus-Proxy Statement. In the merger,
you will receive, for each Roberts share, ADSs unless you decide to receive
ordinary shares. Each ADS represents three ordinary shares. You will receive no
fewer than approximately 1.0427 ADSs, which is equivalent to 3.1280 ordinary
shares, and no more than approximately 1.2802 ADSs, which is equivalent to
3.8407 ordinary shares, for each Roberts common share. The exchange ratio will
be determined based on the average trading price of the ADSs for the fifteen
consecutive trading days ending three trading days before the date the merger
is consummated.

                                 The Companies

Shire Pharmaceuticals Group plc
East Anton
Andover
Hampshire SP10 5RG
ENGLAND
Telephone: (44)1-264-333-455

   Shire is a specialty pharmaceutical company focused primarily on two
therapeutic areas: central nervous system disorders and metabolic/bone
diseases. Shire's principal products include Adderall(R), for the treatment of
Attention Deficit Hyperactivity Disorder, the Calcichew(R) range, promoted
primarily as adjuncts in the treatment of osteoporosis, and Reminyl(R), which
has recently completed Phase III clinical trials, for the treatment of
Alzheimer's disease.

   Shire's revenues come from three sources: sales of products by its own sales
and marketing operations in the U.S., the U.K. and Ireland, and to its
licensees; licensing and development fees; and royalties. Shire recorded
revenues (turnover) of (Pounds)80.3 million and a profit after tax of
(Pounds)6.2 million for the year ended December 31, 1998, or $133.4 million and
$10.3 million, respectively, based upon an exchange rate of (Pounds)0.601 for
each $1.00. Shire used U.K. generally accepted accounting principles in
calculating these amounts. After the transaction, the combined company will
adopt U.S. generally accepted accounting principles for primary reporting
purposes. See "Adoption of U.S. GAAP for Reporting Purposes."

   On October 25, 1999, Shire announced that it had acquired the German and
French subsidiaries of Fuisz Technologies Limited and entered into an agreement
to acquire Fuisz's Italian subsidiary. The purchase price for all three
subsidiaries was $39.5 million. See "Shire After the Merger--Sales and
Marketing."

Roberts Pharmaceutical Corporation
Meridian Center II
4 Industrial Way West
Eatontown, New Jersey 07724
Telephone: (732) 676-1200

   Roberts is an international pharmaceutical company which licenses, acquires,
develops and commercializes post-discovery drugs in selected therapeutic
categories. Roberts was founded to take advantage of the large and growing
opportunity to license, acquire, develop and commercialize post-discovery drugs
in selected therapeutic categories. Roberts has organized its drug development,
acquisition and marketing activities to focus on late-stage development drugs
in Phase II or Phase III clinical trials and currently marketed prescription
pharmaceutical products which do not meet the strategic objectives or profit
thresholds of larger pharmaceutical companies or are made available by

                                       4
<PAGE>

government agencies and research institutions. The therapeutic categories
targeted by Roberts are Cardiovascular, Gynecology/Endocrinology, Urology,
Oncology, Hematology and Gastroenterology.

                              The Special Meeting

Record Date; Shares Entitled to Vote

   Only Roberts shareholders of record at the close of business on October 27,
1999 are entitled to notice of, and to vote at, the special meeting. On the
record date, there were 32,046,720 shares of Roberts common stock outstanding
and entitled to vote which were held by approximately 920 holders of record.
Each holder of record of shares of Roberts common stock on the record date is
entitled to cast one vote per Roberts share, exercisable in person or by a
properly executed proxy, on each matter submitted at the special meeting. See
"The Special Meeting--Record Date; Voting Rights; Voting at the Meeting."

Required Vote

   A quorum for the special meeting will be established if at least a majority
of the Roberts shares are present or represented by proxy. If a quorum is
established, at least two-thirds of the votes cast by the holders of shares of
Roberts common stock present or represented by proxy at the special meeting
must vote in favor of the merger. Brokers who hold Roberts shares as nominees
will not have discretionary authority to vote such Roberts shares in the
absence of instructions from their beneficial owners. Broker "non-votes" and
abstentions count as present for establishing a quorum, but are neither a vote
for nor against the merger.

   Yamanouchi Group Holdings Inc., the owner of 5,048,500 shares of Roberts
common stock, and Robert A. Vukovich, the owner of 1,733,671 shares of Roberts
common stock, have each entered into a shareholder agreement with Shire. They
have each agreed to vote for the merger agreement, which means that
approximately 21.3% of the outstanding shares of common stock of Roberts has
already been committed to vote for the merger agreement. See "The Shareholder
Agreements--Shire Shareholder Agreements."

Revocability of Proxies

   Before the vote at the special meeting, a Roberts shareholder may revoke a
proxy by filing with the Secretary of Roberts a later-dated proxy relating to
the same shares or a written notice of revocation bearing a date later than the
date of the proxy or by attending the special meeting and voting in person. See
"The Special Meeting--Voting of Proxies."

                      The Merger and the Merger Agreement

What You Will Receive in the Merger

   In the merger, each share of Roberts common stock, other than any shares
owned by Shire or Roberts, will be converted into and canceled in exchange for
either ordinary shares or ADSs, each representing three ordinary shares, at the
option of each Roberts shareholder. For each share of Roberts common stock,
Roberts shareholders will receive:

  . a fixed exchange ratio of 3.4122 ordinary shares, or 1.1374 ADSs, if the
    average closing price of the ADSs for the 15 consecutive trading days
    ending the third trading day prior to closing is greater than or equal to
    $23.73 and less than or equal to $29.01;

  . a floating exchange ratio between approximately 3.4122 and approximately
    3.1280 ordinary shares, or approximately 1.1374 and approximately 1.0427
    ADSs, if the average closing price of the ADSs is greater than $29.01 and
    less than or equal to $31.65, which is equivalent to $33.00 per Roberts
    share;

  . a floating exchange ratio between approximately 3.8407 and approximately
   3.4122 ordinary shares, or approximately 1.2802 and approximately 1.1374
   ADSs, if the average closing price of the ADSs is equal to or greater than
   $21.09 and less than $23.73, which is equivalent to $27.00 per Roberts
   share;

                                       5
<PAGE>


  .  a fixed exchange ratio of 3.8407 ordinary shares, or approximately
     1.2802 ADSs, if the average closing price of the ADSs is below $21.09;
     and

  .  a fixed exchange ratio of 3.1280 ordinary shares, or approximately
     1.0427 ADSs, if the average closing price of the ADSs is greater than
     $31.65.

   The following chart briefly summarizes how the exchange ratio for the merger
is calculated:

<TABLE>
<CAPTION>
   Calculated
average trading
 price per ADS                      Number of                                   Hypothetical
    (one ADS                       ADSs to be                                  value received
represents three                 issued for each                                  for each
ordinary shares)                  Roberts share                                Roberts share
- ----------------                 ---------------                               --------------
<S>                              <C>                                           <C>
less than $21.09                  Approximately                                  less than
                                  1.2802                                         $27.00
                                                                                 depending
                                                                                 on the
                                                                                 ADS price


$21.09-$23.72                     27 divided by                                  $27.00
                                  the average
                                  ADS price


$23.73-$29.01                     1.1374                                         between
                                                                                 $27.00 and
                                                                                 $33.00
                                                                                 depending
                                                                                 on the
                                                                                 ADS price


$29.02-$31.65                     33 divided by                                  $33.00
                                  the average
                                  ADS price


more than $31.65                  Approximately                                  more than
                                  1.0427                                         $33.00
                                                                                 depending
                                                                                 on the
                                                                                 ADS price
</TABLE>

   The following chart shows what a holder of 100 shares of Roberts common
stock would receive in the merger at different ADS prices.

<TABLE>
<CAPTION>
                                       Number of
                                      ADSs issued
                                       for every             Market             Fractional
Hypothetical       Exchange           100 Roberts           value of            Share Cash
 ADS Price          Ratio               Shares                ADSs             Consideration
- ------------       --------           -----------           --------           -------------
<S>                <C>                <C>                   <C>                <C>
   20.00            1.2802              128.02              2,560.47                 .47
   21.00            1.2802              128.02              2,688.49                 .49
   22.00            1.2273              122.73              2,700.00               16.00
   23.00            1.1739              117.39              2,700.00                9.00
   24.00            1.1374              113.74              2,729.76               17.76
   25.00            1.1374              113.74              2,843.50               18.50
   26.00            1.1374              113.74              2,957.24               19.24
   27.00            1.1374              113.74              3,070.98               19.98
   28.00            1.1374              113.74              3,184.72               20.72
   29.00            1.1374              113.74              3,298.46               21.46
   30.00            1.1000              110.00              3,300.00                --
   31.00            1.0645              106.45              3,300.00               14.00
   32.00            1.0427              104.27              3,336.53                8.53
   33.00            1.0427              104.27              3,440.80                8.80
   34.00            1.0427              104.27              3,545.07                9.07
   35.00            1.0427              104.27              3,649.33                9.33
</TABLE>

   We have more fully described how the exchange ratio works under the heading
"The Merger Agreement--The Exchange Ratio."

   Based upon the 15 trading days ending prior to and including   , 1999, the
most recent practicable date prior to filing of this document, the average
trading price of the ADSs is $  . Based upon this average, you would receive
ADSs (or    ordinary shares) in the merger for each Roberts share you own.
However, the actual number of ADSs (or ordinary shares) to be issued in the
merger will depend on the market prices of ADSs immediately prior to the
completion of the merger. Depending on the level of such prices, you may
receive more or fewer ADSs or ordinary shares in the merger. We explain this
risk in more detail under the heading "Risk Factors."

                                       6
<PAGE>


   Unless a holder otherwise elects, Shire will provide each Roberts
shareholder with one-third of an ADS for each ordinary share the holder would
be entitled to receive. The ADSs are subject to the terms and conditions of a
deposit agreement. No fractional ADSs or ordinary shares will be issued. You
will instead be paid cash for any fractional ADS or ordinary share to which you
would otherwise be entitled based upon the trading prices of these securities
on the trading day immediately following the merger. See "The Merger
Agreement--Conversion of Roberts Shares" and "--No Fractional ADSs or Ordinary
Shares." With respect to the treatment of options of Roberts, see "The Merger
Agreement--Treatment of Roberts Stock Options."

Benefits of the Merger

   The parties believe that the merger brings together two of the fastest
growing publicly traded specialty pharmaceutical companies, which share a
common strategic vision. Both companies have built effective sales and
marketing organizations to promote specialty products to defined customer
groups. In addition, through selective in-licensing of development compounds,
both companies seek to build long term shareholder value by taking these
compounds through the development and registration process. The principal
benefits of the merger are expected to be:

  .  Broadening of current product portfolios and areas of therapeutic focus;

  .  Addition of products with significant potential that are close to
     reaching the market;

  .  Realization of significant operating benefits;

  .  Increased critical mass in the U.S., the U.K. and Ireland and the
     addition of a Canadian presence to Shire's direct marketing effort;

  .  A larger base from which to build European infrastructure;

  .  Increased attractiveness to obtain product licenses from others;

  .  Complementary research and development and sales and marketing
     infrastructures;

  .  Increased shareholder base and liquidity; and

  .  Greater financial resources to pursue product and/or company
     acquisitions.

Recommendation of the Roberts Board of Directors

   On July 22, 1999, the Roberts board unanimously approved the merger
agreement and the merger as being in the best interests of Roberts and the
Roberts shareholders. The Roberts board unanimously recommends that you vote
FOR the approval and adoption of the merger agreement. See "The Merger--
Roberts' Reasons for the Merger; Recommendation of the Roberts Board of
Directors."

Roberts' Reasons for the Merger

   On July 22, 1999, the Roberts board unanimously determined that the merger
agreement, the option agreement and the transactions contemplated by them were
in the best interests of Roberts' shareholders. The board, therefore, approved
the merger and recommended that the shareholders also approve the merger
agreement and the transactions contemplated by the merger agreement. In
approving these transactions, and recommending approval by the shareholders,
the Roberts board considered:

  .  The consideration offered by Shire and the premium it represented to
     Roberts' share price;

  .  That there were no other formal offers for a business combination;

  .  The opinion of PaineWebber that the merger consideration was fair, from
     a financial point of view, to the Roberts shareholders;

  .  The substantial ownership position that the Roberts shareholders would
     have in the combined company;

  .  That the largest shareholders of Roberts and Shire agreed to vote in
     favor of the merger;

  .  That the combined company would have a broader product offering;

  .  That the combined company would have a broader development portfolio;

                                       7
<PAGE>


  .  That the combined company would have greater financial resources;

  .  That the combined company would increase investor profile and liquidity;

  .  That the merger is a tax-free transaction for the Roberts shareholders;

  .  That the merger would receive pooling of interests accounting treatment
     under U.S. GAAP;

  .  The merger's effect on earnings of the combined company;

  .  The interests in the merger of persons affiliated with Roberts;

  .  The effect of the merger agreement on potential third party proposals
     regarding business combinations;

  .  Other strategic alternatives, including other business combinations and
     remaining independent;

  .  That Adderall(R) is Shire's only major product;

  .  That regulatory approval is not certain;

  .  That pending the merger the conduct of Roberts' business would be
     restricted;

  .  That pending the merger Roberts' business relationships may be damaged
     because of the uncertainty of completing the transaction;

  .  That Roberts would no longer be an independent company; and

  .  That Roberts' shareholders would hold Shire ADSs or ordinary shares.

Opinion of Roberts' Financial Advisor

   In deciding to approve the merger, the Roberts board considered the opinion
of its financial advisor, PaineWebber, that the merger consideration was fair
to Roberts shareholders from a financial point of view.

   The full text of the written opinion of PaineWebber, which sets forth
assumptions made, matters considered, procedures followed and the scope of the
review undertaken, is attached to this Prospectus-Proxy Statement as Annex B.
The written opinion of PaineWebber is not a recommendation as to how you should
vote in regard to the approval and adoption of the merger agreement. We
encourage you to read the opinion of PaineWebber in its entirety.

Interests in the Merger of Persons Affiliated with Roberts

   In considering the recommendation of the Roberts board with respect to the
merger agreement, you should be aware that some of the officers and directors
of Roberts have interests in the merger that are different from and in addition
to your interests.

  .  Some of Roberts' directors will be appointed directors of Shire after
     the merger;

  .  Some executive officers of Roberts will be, or may become, entitled to
     receive a severance payment as a result of the merger;

  .  Any employee whose employment is terminated "without cause" after the
     merger will be entitled to a severance payment;

  .  Options granted under the 1996 Equity Incentive Plan will vest and
     become exercisable after the merger;

  .  As a result of the merger, Roberts' Supplemental Executive Retirement
     Plan will be fully funded and its participants will be credited with 10
     years of service and become vested;

  .  Shire and John T. Spitznagel, President and Chief Executive Officer of
     Roberts, will enter into a consulting agreement; and

  .  Shire has agreed to indemnify Roberts' directors and officers after the
     merger and provide comparable directors' and officers' liability
     insurance for up to six years.

   For further information, see "The Merger --Interests in the Merger of
Persons Affiliated with Roberts."

Anticipated Accounting Treatment

   The merger is intended to qualify as a "pooling of interests" transaction
under U.S. generally accepted accounting principles, which means that the
companies will be treated as if they had always

                                       8
<PAGE>

been combined. The merger will be accounted for as a purchase under U.K. GAAP.
Following the merger, Shire will adopt U.S. GAAP accounting for both U.S. and
U.K. reporting purposes. For more information regarding the impact of this
change in accounting methodology on the combined company see "The Merger--
Anticipated Accounting Treatment and Effects."

Certain U.S. Federal Income Tax Consequences

   For U.S. federal income tax purposes, the parties intend that the merger
will qualify as a reorganization within the meaning of Section 368(a) of the
Internal Revenue Code and that, in general, Roberts shareholders will not
recognize any gain or loss because of the merger, except with respect to cash,
if any, received in lieu of fractional ordinary shares or ADSs.

   The tax consequences of the merger to you will depend on the facts of your
own situation. You should consult your tax advisors to fully understand the tax
consequences of the merger to you.

   You should read carefully the discussion in "Material Tax Consequences" and
other sections of this Prospectus-Proxy Statement. You are urged to consult
your own tax advisors as to the specific tax consequences to you of the merger.

Dissenters' Rights

   Under New Jersey law, you are not entitled to dissenters' rights in
connection with the merger. See "The Merger--Dissenters' Rights" and
"Comparative Rights of Roberts Shareholders and Shire Shareholders--Dissenters'
Rights."

Conditions to the Merger

   Roberts and Shire will not complete the merger unless a number of conditions
are satisfied or waived by them. These include:

  .  approval of the merger and other transactions contemplated by the merger
     agreement by the requisite vote of the respective shareholders of
     Roberts and Shire (this condition may not be waived by Roberts or
     Shire);

  .  there must be no order, injunction, decree or judgment in effect that
     materially restrains or prohibits the merger and there must be no
     pending or threatened proceeding by a governmental authority questioning
     the validity or legality of the merger;

  .  both Roberts and Shire must receive letters from their respective
     independent accountants concurring with management's view regarding the
     availability of "pooling of interests" accounting under U.S. GAAP; and

  .  the ordinary shares to be issued in the merger must be admitted to the
     Official List of the LSE and the listing must have become effective and
     the ADSs must be approved for listing on Nasdaq.

Effective Time of the Merger

   If the merger agreement is approved and adopted by the requisite vote of the
respective shareholders of Roberts and Shire and the other conditions to the
merger are satisfied or, where permissible, waived, the merger will be
consummated and become effective upon the filing of a certificate of merger
with the Secretary of State of the State of New Jersey. See "The Merger
Agreement--General; Effective Time and Effects of the Merger."

Termination of the Merger Agreement

   Roberts and Shire can agree to terminate the merger agreement at any time
prior to completing the merger.

   Either one of them can terminate the merger agreement if it is not in
material breach of the merger agreement and:

  .  the terminating party receives a proposal from a third party which the
     terminating party's board of directors determines is a superior
     proposal;

  .  the merger is not completed by December 31, 1999; or

                                       9
<PAGE>


  .  a governmental authority permanently enjoins or prohibits the merger.

   Each of Roberts and Shire can terminate the merger agreement if:

  .  the board of directors of the other company withdraws or amends or
     adversely modifies its recommendation or approval of the merger to its
     shareholders or fails to reconfirm such recommendation within five
     business days of a request for such a reconfirmation by the other
     company; or

  .  the other company recommends an acquisition transaction proposed by a
     third party; or

  .  the other company breaches or fails to comply with any of its
     representations, warranties or agreements under the merger agreement,
     and such breach cannot be or is not cured prior to December 31, 1999; or

  .  if the other company's shareholders do not approve the merger.

   If Roberts or Shire terminates the merger agreement, depending on the
circumstances of that termination, either Roberts or Shire may become obligated
to pay a termination fee of $30 million. See "The Merger Agreement--
Termination; Effect of Termination."

The Option Agreement

   At the same time the merger agreement was signed, Roberts and Shire entered
into an option agreement, dated as of July 26, 1999. In this agreement, Roberts
granted Shire an option to purchase shares representing up to 19.9% of the
outstanding shares of Roberts common stock at a price per share in cash equal
to $30.00 in the event that Shire is entitled to a termination fee under the
merger agreement. In the event the option is exercised, the maximum total
compensation that Shire may receive from the termination fee under the merger
agreement and any consideration from the sale of Roberts shares acquired from
the exercise of the option is $32 million. See "The Option Agreement."

Governmental and Regulatory Matters

   U.S. antitrust laws prohibit Roberts and Shire from completing the merger
until the transaction has been notified to the Antitrust Division of the
Department of Justice and the Federal Trade Commission and a required waiting
period has expired. On August 10, 1999, Roberts and Shire each filed the
required notification and report forms with the Antitrust Division and the FTC.
The required waiting period expired on September 10, 1999.

   The President of the United States can prohibit an acquisition of a U.S.
company by a foreign person such as Shire if, among other things, the
acquisition would impair the national security of the U.S. Roberts and Shire
made a voluntary filing seeking a finding that the merger does not impair the
national security of the U.S on October 21, 1999.

   In the U.K., the Secretary of State can refer any qualifying merger
situation to the Competition Commission for investigation as to whether the
merger may be expected to operate against the public interest. The merger of
Roberts and Shire is a qualifying merger situation for the purposes of U.K.
law. There is no obligation to obtain prior clearance of a qualifying merger in
the U.K. However, if a qualifying merger is completed without prior clearance
being given, there is a risk that the merger may subsequently be referred to
the Competition Commission and that divestitures might ultimately be required.

   No submission has been made to the U.K. authorities in relation to the
merger, but on July 26, 1999, Shire received from the U.K. Office of Fair
Trading a letter requesting information about the businesses of Shire and
Roberts. A response to that letter was provided on July 29 and was followed by
subsequent communications. On October 18, 1999, the Office of Fair Trading
confirmed that the merger had been cleared.

Comparative Rights of Shareholders

   In the merger, you will have the option to receive either ADSs or ordinary
shares. Each ADS represents three ordinary shares.

                                       10
<PAGE>


   Your rights as a holder of ADSs will in some cases be different from the
rights of a holder of ordinary shares. For example, as an ADS holder, you will
not be entitled to attend, speak and vote at Shire shareholders' meetings
although holders of ordinary shares may do so. However, you will be able to
instruct the depositary how to vote the ordinary shares underlying your ADSs.
Holders of ADSs may generally withdraw and directly hold the ordinary shares
underlying such ADSs at any time.

   There are numerous differences between the rights of a shareholder in
Roberts, a New Jersey corporation, and the rights of a shareholder in Shire, an
English company.

  .  Shareholder Voting Rights. Roberts shareholders are entitled to one vote
     per Roberts share at any Roberts shareholders meeting. At a general
     meeting of shareholders of Shire, holders of ordinary shares are
     entitled to one vote per ordinary share if voting is on a poll and one
     vote per holder present in person at the meeting if voting is by a show
     of hands.

  .  Pre-emptive Rights. Under Roberts' certificate of incorporation, pre-
     emptive rights must be expressly granted by the Roberts board. Under
     English law, a shareholder is entitled to pre-emptive rights with
     respect to new equity issuances for cash unless a special resolution is
     or has been passed in a general meeting of shareholders to the contrary.

  .  Disclosure of Interests. Owners of ordinary shares will be subject to
     different, and in some cases more stringent, notification, disclosure
     and other obligations under English law and under applicable regulations
     of U.K. non-governmental authorities than those to which owners of
     shares of Roberts common stock are subject under New Jersey law. Under
     the terms of the deposit agreement, holders of Shire ADSs are bound to
     comply with the same notification and disclosure requirements as Shire
     shareholders.

   You should also be aware that it may be difficult to effect service of a
process to begin a lawsuit against directors and officers of Shire who are not
residents of the U.S.

Adoption of U.S. GAAP for Reporting Purposes

   Historically, Shire has presented accounts prepared under U.K. GAAP in both
its annual and interim reports, including those distributed to U.S.
shareholders and within filings made with the SEC. Shire's annual reports have
incorporated a reconciliation of earnings and net assets to U.S. GAAP. As a
"foreign private issuer," full U.S. GAAP financial statements have not been
required. A company is deemed to be a "foreign private issuer" if it is
organized under the laws of a non-U.S. country and does not have more than 50%
ownership of voting shares held by U.S. resident shareholders.

   Given that it is anticipated that more than 50% of the combined company's
shareholders will be U.S. residents, Shire is likely to lose its foreign
registrant status. As a result, publication of full U.S. GAAP financial
statements will be required in all SEC filings and distributions to U.S.
shareholders. In order to allow for consistency in reporting financial results
to U.S. and U.K. shareholders, the combined company intends to adopt U.S. GAAP
for primary reporting purposes in the U.K. Summary financial statements
prepared as required by U.K. company law and a reconciliation of the combined
company's financial results to U.K. GAAP will be provided in the footnotes of
its annual report. Interim reports circulated to U.K. shareholders will meet
the minimum requirements of the London Stock Exchange for provision of U.K.
GAAP information. Furthermore, full U.K. GAAP statutory accounts will be
prepared to satisfy U.K. reporting requirements under the Companies Act 1985.
Such accounts are required to be filed on an annual basis, within seven months
of the accounting period end, and will be publicly available.

   There are certain differences between U.S. GAAP and U.K. GAAP. The principal
differences are summarized in note 24 to Shire's Audited Consolidated Financial
Statements incorporated by reference in this Prospectus-Proxy Statement and
include the following:

 i. Accounting for business combinations

  (a) Goodwill

   Prior to December 31, 1998, goodwill arising from the acquisition of a
business could be written

                                       11
<PAGE>

off to retained earnings under U.K. GAAP. This treatment is not allowed by U.S.
GAAP, which requires goodwill to be capitalized and amortized over a period of
up to 40 years. Under U.S. GAAP, Shire amortizes goodwill over a period of 5-30
years on a straight-line basis. The goodwill is evaluated annually for
realisability based on expectations of undiscounted cash flows and earnings
from operations for each subsidiary having a material goodwill balance.
Impairments to goodwill are recognized if future expected cash flows are not
sufficient to recover the goodwill. If a material impairment were identified,
goodwill would be written down to its fair value.

  (b) In-process research and development

   Under U.K. GAAP, fair values are not attributed to in-process research and
development. Under U.S. GAAP, acquired research and development is expensed to
the extent that technological feasibility has not been established and the
technology has no future alternative uses. A charge of (Pounds)50,626,000 was
recorded in 1997 under U.S. GAAP, which related to the write-off of in-process
research and development in conjunction with the Shire Laboratories Inc.
acquisition.

 ii. Deferred taxation

   Under U.K. GAAP, deferred tax is provided in respect of timing differences
only to the extent that liabilities are expected to occur in the foreseeable
future. Net deferred tax assets are only recognized to the extent that they are
expected to be recoverable without any replacement by equivalent debit
balances. Under U.S. GAAP, deferred taxation is recorded in respect of all
temporary differences between the tax bases and book values of assets and
liabilities which will result in taxable or tax deductible amounts in future
years. Deferred tax assets under U.S. GAAP are recognized to the extent that it
is more likely than not that they will be realized.

   Under U.K. GAAP, deferred taxes are not normally recognized in respect of
the difference between the fair value attributable to net assets of an acquired
business and their underlying tax basis. Under U.S. GAAP, such deferred tax
attributes are recognized in the allocation of values. Any subsequent
adjustments to the valuation allowances established at the date of acquisition
against deferred tax assets recognized on that date are treated as an
adjustment to the purchase price. Accordingly, it has no effect on net
income/(loss) and shareholder's equity in relation to deferred tax assets
arising on acquisition. Valuation allowances against deferred tax assets have
not been provided to the extent that future taxable income and tax planning
strategies are expected to enable losses brought forward to be utilized.

 iii. Share options

   Under U.K. GAAP, a compensation expense must generally be recognized on
share option schemes based on the difference between the fair value of the
shares at the date of grant and the exercise price, over the vesting period of
the options. A compensation expense does not have to be recognized for certain
schemes that are open to all employees on similar terms at a discount against
the fair value of the shares of not more than 20 percent.

   In contrast, under U.S. GAAP, a compensation expense must generally be
recognized based on the difference between the fair value of the shares at the
measurement date and the exercise price, over the vesting period of the
options. The measurement date for calculating compensation cost is the date on
which both the exercise price and the number of shares under option are known
with certainty. If a fixed price option for a specific number of shares is
granted, compensation cost is the excess of the quoted market price of the
stock at the date of the grant over the exercise price of such option. Such
compensation cost is amortized over the vesting period of the option. However,
where either the strike price or number of shares underlying an option is
uncertain, "variable option accounting" is required, whereby the quoted market
price used in the measurement of compensation cost is not the price at the
grant date but the price at the measurement date. Estimates of compensation
cost are recorded before the measurement date based on the quoted market price
of the stock at intervening dates. Recorded compensation expense between the

                                       12
<PAGE>

grant date and the measurement date may either increase or decrease because
changes in the quoted market price of the stock require recomputations of the
estimated compensation cost.

   A number of Shire's currently outstanding options include performance
incentive clauses which tie the amount of shares under option to the stock
market performance of Shire ordinary shares. As the number of shares under
option is dependent on the stock price performance of Shire ordinary shares,
such options require "variable option accounting," leading to a compensation
charge which is dependent on the underlying performance of Shire ordinary
shares. As the Shire ordinary share price has appreciated in recent periods,
the U.S. GAAP compensation charges for the years ended December 31, 1997 and
1998 and for the nine months ended September 30, 1999 are significantly higher
than the corresponding U.K. GAAP compensation charges. Further details of
Shire's share option schemes are summarized on page 46 of Shire's Annual Report
incorporated by reference in this Prospectus-Proxy Statement.

                                       13
<PAGE>


   The following two tables illustrate the historical reconciliation of net
profit/(loss) and the effect of such reconciliation on earnings per share.

Reconciliation of net profit/(loss) from U.K. GAAP to U.S. GAAP

<TABLE>
<CAPTION>
                                 Year  ended December 31,      Nine Months Ended
                               ------------------------------    September 30,
                                   1998            1997              1999
                               -------------  ---------------  -----------------
<S>                            <C>            <C>              <C>
Net profit/(loss) as reported
 under U.K. GAAP.............  (Pounds)6,247  (Pounds)   (421)  (Pounds)17,363
Adjustments for:
  Write-off of in-process
   research and development..            --           (50,626)             --
  Amortization of goodwill...         (6,709)          (2,459)          (5,103)
  Recognition of deferred tax
   asset.....................          7,765            1,312            1,771
  Share option compensation
   costs.....................         (5,124)          (1,412)          (8,397)
Net profit/(loss) as reported
 under U.S. GAAP.............  (Pounds)2,179  (Pounds)(53,606)  (Pounds) 5,634

Comparison of earnings/(loss) per share under U.K. GAAP and U.S. GAAP

<CAPTION>
                                  Year ended December 31,      Nine Months Ended
                               ------------------------------    September 30,
                                   1998            1997              1999
                               -------------  ---------------  -----------------
<S>                            <C>            <C>              <C>
U.K. GAAP
  Basic earnings/(loss) per
   ordinary share............           4.5p             0.4p            12.2p
  Diluted earnings/(loss) per
   ordinary share............           4.3p             0.4p            11.7p
U.S. GAAP
  Basic earnings/(loss) per
   ordinary share............           1.6p           (57.6)p            3.9p
  Diluted earnings/(loss) per
   ordinary share............           1.5p           (57.6)p            3.8p
</TABLE>

                                       14
<PAGE>


            Summary Historical Consolidated Financial Data of Shire

                             Summary Financial Data

   The following summary financial information of Shire for each of the fiscal
periods in the five year period ended December 31, 1998 has been derived from
Shire's Audited Consolidated Financial Statements and the notes to such
financial statements incorporated by reference in this Prospectus-Proxy
Statement. Summary financial information for the nine month period to September
30, 1999 has been derived from Shire's unaudited consolidated financial
statements for the nine months to September 30, 1999. The selected financial
data has been prepared using U.K. and U.S. GAAP, which differ in certain
respects. The principal differences between U.K. GAAP and U.S. GAAP are
summarized in note 24 to Shire's audited consolidated financial statements
incorporated by reference in this Prospectus-Proxy Statement. Following the
merger, Shire intends to report under U.S. GAAP, with selected U.K. GAAP
reconciliation. See "Adoption of U.S. GAAP for Reporting Purposes." The results
of operations for the nine months ended September 30, 1999 are not necessarily
indicative of the results of operations to be expected for the fiscal year
ending December 31, 1999.

<TABLE>
<CAPTION>
                         15 Months
                           Ended
                         June 30,
                          1994(1)         1995
                       -------------  -------------
<S>                    <C>            <C>
Statement of
 Operations
 Data:
U.K. GAAP
Turnover/(revenues)..  (Pounds)7,465  (Pounds)6,102
Operating
 profit/(loss)..              (2,349)        (6,127)
Profit/(loss) on
 ordinary
 activities
 before
 taxation.......              (2,244)        (7,197)
Profit/(loss) on
 ordinary
 activities
 after
 taxation.......              (2,190)        (7,200)
Fully diluted
 earnings/(loss)
 per ordinary
 share..........              (0.119)        (0.394)
Weighted average
 ordinary shares
 outstanding....              18,288         18,289
U.S. GAAP
Revenues........
Income/(loss)
 from operations
 before write-
 off of in-
 process
 research and
 development....
(Loss)/income
 from
 operations.....
(Loss)/income
 before income
 taxes..........
Net
 (loss)/income..
Fully diluted
 net
 (loss)/income
 per ordinary
 share(4).......
Fully diluted
 net
 (loss)/income
 per ADS........
<CAPTION>
                        Year Ended                                                Year Ended                  Nine Months Ended
                         June 30,                   Six Months                   December 31,                   September 30,
                       ---------------------------     Ended       ------------------------------------------ -----------------
                                                   December 31,                                                Actual
                            1996            1997       1997           1997(2)           1998         1998(3)    1999      1999(3)
                       --------------- ----------- --------------- --------------- --------------- ---------------------- ---------
                                                                                                        (unaudited)     (unaudited)
                                (in thousands, except per ordinary share and per ADS amounts)
<S>                    <C>             <C>             <C>              <C>             <C>             <C>         <C>        <C>
Statement of
 Operations
 Data:
U.K. GAAP
Turnover/(revenues)..  (Pounds)21,043 (Pounds)23,072 (Pounds) 28,605 (Pounds)41,798 (Pounds)80,328  $131,738 (Pounds)92,516 $151,726
Operating
 profit/(loss)..               2,569          (1,399)          2,230          1,582          7,879    12,922         21,501   35,262
Profit/(loss) on
 ordinary
 activities
 before
 taxation.......               2,722            (146)          2,452          2,411          9,099    14,922         23,153   37,971
Profit/(loss) on
 ordinary
 activities
 after
 taxation.......               2,555            (146)           (380)          (421)         6,247    10,245         17,363   28,475
Fully diluted
 earnings/(loss)
 per ordinary
 share..........               0.057          (0.002)         (0.003)        (0.004)         0.043     0.071          0.117    0.192
Weighted average
 ordinary shares
 outstanding....              45,208          67,153         112,660         93,145        144,399   144,399        148,526  148,526
U.S. GAAP
Revenues........              21,043          23,072          28,605         41,798         80,328   131,738         92,516  151,726
Income/(loss)
 from operations
 before write-
 off of in-
 process
 research and
 development....               2,302          (1,659)         (1,469)        (2,289)        (2,143)   (3,514)        10,018   16,430
(Loss)/income
 from
 operations.....             (12,426)        (52,285)         (1,469)       (52,915)        (2,143)   (3,514)        10,018   16,430
(Loss)/income
 before income
 taxes..........             (12,273)        (51,032)         (1,247)       (52,086)          (923)   (1,514)        11,670   19,139
Net
 (loss)/income..             (12,189)        (50,238)         (2,857)       (53,606)         2,179     3,574          5,634    9,240
Fully diluted
 net
 (loss)/income
 per ordinary
 share(4).......               (0.28)          (0.75)          (0.03)         (0.57)          0.02      0.03           0.04     0.06
Fully diluted
 net
 (loss)/income
 per ADS........               (0.83)          (2.24)          (0.08)         (1.73)          0.05      0.07           0.11     0.18
</TABLE>

                                       15
<PAGE>

            Summary Historical Consolidated Financial Data of Shire

                             Summary Financial Data

<TABLE>
<CAPTION>
                                   As of June 30,                                As of December 31,
                  ---------------------------------------------------  ----------------------------------------
                    1994(1)      1995         1996          1997          1997(2)           1998       1998(3)
                  ----------- -----------  -----------  -------------  --------------  --------------  --------
<S>               <C>         <C>          <C>          <C>            <C>             <C>             <C>
Balance Sheet
 Data:
U.K. GAAP
Fixed assets....  (Pounds)503 (Pounds)447  (Pounds)578  (Pounds)3,436  (Pounds)11,950  (Pounds)12,609  $ 20,679
Cash and current
 investments....          960       2,068       25,425         16,875          10,283          29,665    48,631
Secured loan
 notes..........          --       (5,212)         --             --              --              --        --
Other net
 current assets
 (liabilities)..          358      (1,161)       1,893         (4,155)         (1,047)          9,828    16,118
Creditors due in
 more than one
 year...........          --          --           --          (2,211)        (11,246)         (1,508)   (2,473)
Provision for
 liabilities and
 charges........          --          --        (2,750)           --              --              --        --
                  ----------- -----------  -----------  -------------  --------------  --------------  --------
Net assets......        1,821      (3,858)      25,146         13,945           9,940          50,594    82,975
U.S. GAAP
Cash and cash
 equivalents....                                25,425         16,875          10,283          29,665    48,651
Other current
 assets.........                                 5,880          7,829          17,475          24,212    39,708
Other assets....                                 5,425         15,862         153,109         155,250   254,610
                                           -----------  -------------  --------------  --------------  --------
Total assets....                                36,730         40,566         180,867         209,127   342,969
Current
 liabilities....                                 3,987          5,781          18,522          14,384    23,590
Other
 liabilities....                                 2,750          2,211          11,246           1,508     2,473
Shareholders'
 equity.........                                29,993         32,574         151,099         193,235   316,906
                                           -----------  -------------  --------------  --------------  --------
Total
 liabilities and
 shareholders'
 equity.........                                36,730         40,566         180,867         209,127   342,969
<CAPTION>
                    As of September 30,
                  -------------------------
                       1999       1999(3)
                  --------------- ---------
<S>               <C>             <C>
Balance Sheet
 Data:
U.K. GAAP
Fixed assets....  (Pounds)17,885  $ 29,282
Cash and current
 investments....          52,508    86,113
Secured loan
 notes..........          (5,354)   (8,781)
Other net
 current assets
 (liabilities)..           7,899    12,954
Creditors due in
 more than one
 year...........          (2,702)   (4,431)
Provision for
 liabilities and
 charges........             --        --
                  --------------- ---------
Net assets......          70,236   115,137
U.S. GAAP
Cash and cash
 equivalents....          52,508    86,113
Other current
 assets.........          48,318    79,242
Other assets....         137,849   226,072
                  --------------- ---------
Total assets....         238,675   391,427
Current
 liabilities....          26,428    43,342
Other
 liabilities....           2,702     4,431
Shareholders'
 equity.........         209,545   343,654
                  --------------- ---------
Total
 liabilities and
 shareholders'
 equity.........         238,675   391,427
</TABLE>
- --------
(1) In 1994, Shire elected to change its fiscal year end from March 31 to June
    30.

(2) During 1997, Shire changed its fiscal year end from June 30 to December 31.
    The results for the year ended December 31, 1997 are presented for
    comparative purposes. These accounts do not comprise statutory accounts
    within the meaning of the Companies Act 1985 since they are drawn up for a
    non-statutory period.

(3) Translation of pounds sterling into dollars has been made at the rate of
    (Pounds)1.00 = $1.64 (the noon buying rate on September 30, 1999). Such
    translation is provided solely for the convenience of the reader and does
    not reflect financial information based on generally accepted accounting
    principles for foreign currency translations.

(4) Includes the write-off of that portion of the purchase price of the
    acquisitions of Shire Pharmaceutical Contracts Limited, Shire Laboratories
    Inc. and Shire Richwood Inc. allocated to in-process research and
    development where technological feasibility has not yet been established
    and for which there were no alternative future uses. Such write-offs amount
    to (Pounds)14,728,000 for the fiscal year ended June 30, 1996 and
    (Pounds)50,626,000 for the fiscal year ended June 30, 1997.

                                       16
<PAGE>


           Summary Historical Consolidated Financial Data of Roberts

   The following table presents the selected consolidated financial data for
Roberts as of the dates and for the periods indicated. The selected
consolidated financial data for each of the five years in the period ended
December 31, 1998 have been derived from the audited Consolidated Financial
Statements of Roberts, which are incorporated by reference in this Prospectus-
Proxy Statement. The selected consolidated financial data as of and for the
periods ended September 30, 1998 and 1999 have been derived from unaudited
Consolidated Financial Statements of Roberts which, in the opinion of Roberts'
management, have been prepared on a basis substantially consistent with the
audited financial statements and include all adjustments, consisting of normal
recurring adjustments, necessary to present fairly the information for the
period. The results of such interim periods are not necessarily indicative of
the results for the full fiscal year. The data presented below should be read
in conjunction with Roberts' audited Consolidated Financial Statements for each
of the fiscal years in the five year period ended December 31, 1998 and the
unaudited Consolidated Financial Statements as of and for the periods ended
September 30, 1998 and 1999, which are incorporated in this Prospectus-Proxy
Statement by reference.
<TABLE>
<CAPTION>
                                                                             Nine Months Ended
                                   Years Ended December 31,                    September 30,
                          -------------------------------------------------- -----------------
                           1994      1995      1996         1997      1998     1998     1999
                          -------  --------  --------     --------  -------- -------- --------
                             (in thousands, except per share data)              (unaudited)
<S>                       <C>      <C>       <C>          <C>       <C>      <C>      <C>
Statement of Operations
 Data:
Total Revenue...........  $89,020  $113,427  $ 98,111     $122,508  $175,445 $119,925 $147,493
Operating Income (Loss)
 from Continuing
 Operations.............   25,802     6,873   (50,195)(1)     (762)   27,378   16,452   35,567
Income (Loss) from
 Continuing Operations..   20,618     2,703   (34,275)       2,517    16,787   10,208   19,757
Net (Loss) Income from
 Discontinued
 Operations.............   (1,206)  (27,045)      556          --        --       --       --
Net Income (Loss).......   19,412   (24,342)  (33,719)       2,517    16,787   10,208   19,757
Earnings (Loss) Per
 Share of Common Stock
 from Continuing
 Operations--Basic......     l.12       .15     (2.47)(2)      .06       .54      .33      .62
(Loss) Earnings Per
 Share of Common Stock
 from Discontinued
 Operations--Basic......     (.06)    (1.46)      .03          --        --       --       --
Earnings (Loss) Per
 Share of Common Stock--
 Basic..................     1.06     (1.31)    (2.44)         .06       .54      .33      .62
Average Number of Common
 Shares--Basic
 Outstanding............   18,400    18,536    19,133       29,414    31,049   30,912   31,716
Earnings (Loss) Per
 Share of Common Stock
 from Continuing
 Operations--Diluted....  $  1.10  $    .15  $  (2.47)(2) $    .06  $    .53 $    .33 $    .61
(Loss) Earnings Per
 Share of Common Stock
 from Discontinued
 Operations--Diluted....     (.06)    (1.45)      .03          --        --       --       --
Earnings (Loss) Per
 Share of Common Stock--
 Diluted................     1.04     (1.30)    (2.44)         .06       .53      .33      .61
Average Number of Common
 Shares--Diluted
 Outstanding............   18,708    18,623    19,133       29,497    31,460   31,297   32,283
</TABLE>

                                       17
<PAGE>

<TABLE>
<CAPTION>
                                                                       As of September
                                      As of December 31,                     30,
                         -------------------------------------------- -----------------
                           1994     1995     1996     1997     1998     1998     1999
                         -------- -------- -------- -------- -------- -------- --------
                                                                                   (unaudited)
<S>                      <C>      <C>      <C>      <C>      <C>      <C>      <C>      <C> <C> <C> <C> <C>
Balance Sheet Data:
Total Assets............ $336,192 $340,290 $372,225 $367,855 $526,236 $514,913 $550,987
Long-Term Debt and
 Redeemable Preferred
 Stock (excluding
 current installments)..   22,411   16,183   10,639   10,327  126,739  130,302  122,188
Total Shareholders'
 Equity.................  259,129  235,467  309,759  317,303  341,810  334,330  367,340
</TABLE>

   (1) Intangible Dispositions and Write-Offs. During the fourth quarter of
1996, Roberts completed the sale of the majority of its non-core
nonprescription products along with the NUCOFED and QUIBRON brands in two
independent sales transactions. These sales, net of proceeds, resulted in a
one-time, non-cash write-off of $11.9 million, which amounted to $7.6 million
net of taxes. Also, during the fourth quarter of 1996, Roberts expensed certain
purchased development products and recorded an impairment loss of long-lived
intangible assets totaling $25.4 million, which amounted to $17.8 million net
of taxes.

   The loss from operations and net loss for the year ending December 31, 1996
increased as a result of the purchase of development products and the sale and
writedown of the intangible assets in the amounts of $37.3 million for
operating income and $25.4 million for net loss.

   (2) According to a position taken by the SEC staff, effective March 13,
1997, on accounting for preferred stock which is convertible at a discount to
market, Roberts recorded a charge of $11.6 million, which for earnings per
share purposes amounted to $.61 per share. This charge to earnings per share is
consistent with the SEC staff's position that the 10% discount available to
holders of Roberts' 5% Convertible Preferred Stock should be amortized between
the issuance date and the first date that conversion could occur, which is the
earlier of the date on which the registration statement is declared effective
or the close of business on the 91st day following the original issuance of the
5% Convertible Preferred Stock.

   To clarify the adjustments indicated above, a reconciliation of dilutive
Earnings Per Share for the twelve months ended December 31, 1996 is composed of
the following elements:

<TABLE>
   <S>                                                                <C>
   Net (loss) from continuing operations before the consideration of
    purchased research and development, write-off and the sale of
    intangible assets, the recognition of the discount upon the
    issuance of 5% Preferred Stock or preferred dividends............ $ (.47)
   Purchased research and development and the write-off and sale of
    intangible assets................................................  (1.33)
   5% Preferred Stock dividends......................................   (.06)
   Issuance of 5% Preferred Stock convertible into common stock at a
    10% discount to market........................................... $ (.61)
                                                                      ------
                                                                        (.67)
   Net (loss) from continuing operations.............................  (2.47)
   Income from discontinued operations...............................    .03
   (Loss) attributable to common stock............................... $(2.44)
                                                                      ======
</TABLE>

                                       18
<PAGE>

              Summary Unaudited Pro Forma Combined Financial Data

   The following unaudited pro forma combined financial statements give effect
to the proposed merger of Shire and Roberts as a pooling of interests under
U.S. GAAP. The unaudited pro forma condensed balance sheet presents the
combined financial position of Shire and Roberts as of September 30, 1999
assuming that the proposed merger has occurred as of September 30, 1999. Such
pro forma information is based upon the historical financial statements of
Shire and Roberts and has been prepared to illustrate the effects of the
merger. In calculating the Shire Roberts pro forma information, an average ADS
trading price in the range $23.73 to $29.01 has been assumed. Following the
merger it is anticipated that Shire will no longer qualify as a foreign private
issuer. Shire, as the continuing registrant, will adopt U.S. GAAP as the basis
for financial reporting. The pro forma combined financial data should be read
in conjunction with the historical financial statements of Shire and Roberts
incorporated herein by reference. The pro forma combined financial data are
presented for illustrative purposes only and are not necessarily indicative of
any future results of operations or the results that might have occurred if the
merger had actually occurred on the indicated dates.

                                       19
<PAGE>

            Unaudited Pro Forma Combined Condensed Income Statement

                      Nine months ended September 30, 1999

<TABLE>
<CAPTION>
                                          Shire                                    Roberts             Shire Roberts Pro Forma
                   ------------------------------------------------------  -------------------------  --------------------------
                                   Adjustments                    U.S.       U.S.                                        U.S.
                     U.K. GAAP         (1)        U.S. GAAP      GAAP(2)    GAAP(3)    U.S. GAAP(4)    U.S. GAAP(5)     GAAP(6)
                   --------------  -----------  --------------  ---------  ---------  --------------  ---------------  ---------
                                       (in thousands, except per ordinary share and per ADS amounts)
<S>                <C>             <C>          <C>             <C>        <C>        <C>             <C>              <C>
Total revenue....  (Pounds)92,516  (Pounds)--   (Pounds)92,516  $ 149,876  $ 147,493  (Pounds)91,045  (Pounds)183,561  $ 297,369
Operating
 expenses........         (71,015)     (11,483)        (82,498)  (133,647)  (111,926)        (69,090)        (151,588)  (245,573)
Operating
 income/(loss)...          21,501      (11,483)         10,018     16,229     35,567          21,955           31,973     51,796
Interest income..           1,679          --            1,679      2,720      2,780           1,716            3,395      5,500
Interest
 expense.........             (27)         --              (27)       (44)    (7,270)         (4,488)          (4,515)    (7,314)
Other, net.......             --           --              --         --        (449)           (277)            (277)      (449)
Income/(loss)
 before income
 taxes...........          23,153      (11,483)         11,670     18,905     30,628          18,906           30,576     49,533
Income taxes.....          (5,790)        (246)         (6,036)    (9,778)   (10,871)        (6,710)          (12,746)   (20,649)
Net
 income/(loss)...          17,363      (11,729)          5,634      9,127     19,757          12,196           17,830     28,884
Earnings/(loss)
 per ordinary
 share
 -- basic........            0.12          --             0.04       0.06       0.62            0.38              --         --
 -- diluted......            0.12          --             0.04       0.06       0.61            0.38              --         --
Weighted average
 ordinary shares
 outstanding
 -- basic........         142,769          --          142,769    142,769     31,716          31,716              --         --
 -- diluted......         148,526          --          148,526    148,526     32,283          32,283              --         --
Pro forma
 information
 based on
 exchange ratio
 of 3.4122 (10)
Pro forma
 earnings/(loss)
 per ordinary
 share
 -- basic........                                                                                                0.07       0.12
 -- diluted......                                                                                                0.07       0.11
Pro forma
 weighted average
 ordinary shares
 outstanding
 -- basic........                                                                                             250,990    250,990
 -- diluted......                                                                                             258,682    258,682
Pro forma
 earnings/(loss)
 per ADS
 -- basic........                                                                                                0.21       0.35
 -- diluted......                                                                                                0.21       0.33
Pro forma
 information
 based on
 exchange ratio
 of 3.8407 (10)
Pro forma
 earnings/(loss)
 per ordinary
 share
 -- basic........                                                                                                0.07       0.11
 -- diluted......                                                                                                0.07       0.11
Pro forma
 weighted average
 ordinary shares
 outstanding
 -- basic........                                                                                             264,581    264,581
 -- diluted......                                                                                             272,515    272,515
Pro forma
 earnings/(loss)
 per ADS
 -- basic........                                                                                                0.20       0.33
 -- diluted......                                                                                                0.20       0.32
Pro forma
 information
 based on
 exchange ratio
 of 3.1280 (10)
Pro forma
 earnings/(loss)
 per ordinary
 share
 -- basic........                                                                                                0.07       0.12
 -- diluted......                                                                                                0.07       0.12
Pro forma
 weighted average
 ordinary shares
 outstanding
 -- basic........                                                                                             241,977    241,977
 -- diluted......                                                                                             249,507    249,507
Pro forma
 earnings/(loss)
 per ADS
 -- basic........                                                                                                0.22       0.36
 -- diluted......                                                                                                0.21       0.35
</TABLE>

                                       20
<PAGE>

            Unaudited Pro Forma Combined Condensed Income Statement

                          Year Ended December 31, 1998

<TABLE>
<CAPTION>
                     U.K. GAAP
                   --------------
<S>                <C>
Total revenue....  (Pounds)80,328
Operating
 expenses........         (72,449)
Operating
 income/(loss)...           7,879
Interest income..           1,434
Interest
 expense.........            (214)
Other, net.......             --
Income/(loss)
 before income
 taxes...........           9,099
Income taxes.....          (2,852)
Net
 income/(loss)...           6,247
Earnings/(loss)
 per ordinary
 share
 -- basic........            0.05
 -- diluted......            0.04
Weighted average
 ordinary shares
 outstanding
 -- basic........         136,924
 -- diluted......         144,399
Pro forma
 information
 based on
 exchange ratio
 of 3.4122(10)
Pro forma
 earnings/(loss)
 per ordinary
 share
 -- basic........
 -- diluted......
Pro forma
 weighted average
 ordinary shares
 outstanding
 -- basic........
 -- diluted......
Pro forma
 earnings/(loss)
 per ADS
 -- basic........
 -- diluted......
Pro forma
 information
 based on
 exchange ratio
 of 3.8407(10)
Pro forma
 earnings/(loss)
 per ordinary
 share
 -- basic........
 -- diluted......
Pro forma
 weighted average
 ordinary shares
 outstanding
 -- basic........
 -- diluted......
Pro forma
 earnings/(loss)
 per ADS
 -- basic........
 -- diluted......
Pro forma
 information
 based on
 exchange ratio
 of 3.1280(10)
Pro forma
 earnings/(loss)
 per ordinary
 share
 -- basic........
 -- diluted......
Pro forma
 weighted average
 ordinary shares
 outstanding
 -- basic........
 -- diluted......
Pro forma
 earnings/(loss)
 per ADS
 -- basic........
 -- diluted......
<CAPTION>
                          Shire                                     Roberts              Shire Roberts Pro Forma
                   --------------------------------------- --------------------------- -----------------------------
                   Adjustments                    U.S.       U.S.                                           U.S.
                       (1)        U.S. GAAP      GAAP(2)    GAAP(3)    U.S. GAAP(4)      U.S. GAAP(5)     GAAP(6)
                   ------------ --------------- ---------- ---------- ---------------- ----------------- -----------
                         (in thousands, except per ordinary share and per ADS amounts)
<S>                <C>          <C>             <C>        <C>        <C>              <C>               <C>
Total revenue....  (Pounds)--   (Pounds)80,328  $ 133,344  $ 175,445  (Pounds)105,690  (Pounds)1186,018  $  308,789
Operating
 expenses........      (10,022)        (82,471)  (136,902)  (148,067)         (89,197)         (171,668)  (284 ,969)
Operating
 income/(loss)...      (10,022)         (2,143)    (3,558)    27,378           16,493            14,350      23,820
Interest income..          --            1,434      2,380      4,108            2,475             3,909       6,488
Interest
 expense.........          --             (214)      (355)    (6,157)          (3,709)           (3,923)     (6,512)
Other, net.......          --              --         --        (318)            (192)             (192)       (318)
Income/(loss)
 before income
 taxes...........      (10,022)           (923)    (1,533)    25,011           15,067            14,144      23,478
Income taxes.....        5,954           3,102      5,149     (8,224)          (4,954)           (1,852)     (3,075)
Net
 income/(loss)...       (4,068)          2,179      3,616     16,787           10,113            12,292      20,403
Earnings/(loss)
 per ordinary
 share
 -- basic........          --             0.02       0.03       0.54             0.33               --          --
 -- diluted......          --             0.02       0.03       0.53             0.32               --          --
Weighted average
 ordinary shares
 outstanding
 -- basic........          --          136,924    136,924     31,049           31,049               --          --
 -- diluted......          --          144,399    144,399     31,460           31,460               --          --
Pro forma
 information
 based on
 exchange ratio
 of 3.4122(10)
Pro forma
 earnings/(loss)
 per ordinary
 share
 -- basic........                                                                                  0.05        0.08
 -- diluted......                                                                                  0.05        0.08
Pro forma
 weighted average
 ordinary shares
 outstanding
 -- basic........                                                                               242,869     242,869
 -- diluted......                                                                               251,747     251,747
Pro forma
 earnings/(loss)
 per ADS
 -- basic........                                                                                  0.15        0.25
 -- diluted......                                                                                  0.15        0.24
Pro forma
 information
 based on
 exchange ratio
 of 3.8407(10)
Pro forma
 earnings/(loss)
 per ordinary
 share
 -- basic........                                                                                  0.05        0.08
 -- diluted......                                                                                  0.05        0.08
Pro forma
 weighted average
 ordinary shares
 outstanding
 -- basic........                                                                               256,173     256,173
 -- diluted......                                                                               265,228     265,228
Pro forma
 earnings/(loss)
 per ADS
 -- basic........                                                                                  0.14        0.24
 -- diluted......                                                                                  0.14        0.23
Pro forma
 information
 based on
 exchange ratio
 of 3.1280(10)
Pro forma
 earnings/(loss)
 per ordinary
 share
 -- basic........                                                                                  0.05        0.09
 -- diluted......                                                                                  0.05        0.08
Pro forma
 weighted average
 ordinary shares
 outstanding
 -- basic........                                                                               234,045     234,045
 -- diluted......                                                                               242,806     242,806
Pro forma
 earnings/(loss)
 per ADS
 -- basic........                                                                                  0.16        0.26
 -- diluted......                                                                                  0.15        0.25
</TABLE>

                                       21
<PAGE>

            Unaudited Pro Forma Combined Condensed Income Statement

                       Six Months Ended December 31, 1997

<TABLE>
<CAPTION>
                                          Shire                                     Roberts             Shire Roberts Pro Forma
                   -------------------------------------------------------  -------------------------  --------------------------
                        U.K.        Adjustments       U.S.          U.S.      U.S.         U.S.             U.S.          U.S.
                        GAAP            (1)           GAAP        GAAP(2)   GAAP(3)       GAAP(4)          GAAP(5)       GAAP(6)
                   ---------------  -----------  ---------------  --------  --------  ---------------  ---------------  ---------
                                        (in thousands, except per ordinary share and per ADS amounts)
<S>                <C>              <C>          <C>              <C>       <C>       <C>              <C>              <C>
Total revenue....  (Pounds) 28,605  (Pounds)--   (Pounds) 28,605  $ 46,912  $ 65,892  (Pounds) 40,178  (Pounds) 68,783  $ 112,804
Operating
 expenses........          (26,375)      (3,699)         (30,074)  (49,321)  (67,918)         (41,413)         (71,487)  (117,239)
Operating
 income/(loss)...            2,230       (3,699)          (1,469)   (2,409)   (2,026)          (1,235)          (2,704)    (4,435)
Interest income..              337          --               337       553     2,503            1,526            1,863      3,056
Interest
 expenses........             (115)         --              (115)     (189)     (323)            (197)            (312)      (512)
Other, net.......              --           --               --        --     (2,167)          (1,321)          (1,321)    (2,167)
Income/(loss)
 before income
 taxes...........            2,452       (3,699)          (1,247)   (2,045)   (2,013)          (1,227)          (2,474)    (4,058)
Income taxes.....           (2,832)       1,222           (1,610)   (2,640)    2,332            1,422             (188)      (308)
Net
 income/(loss)...             (380)      (2,477)          (2,857)   (4,685)      319              195           (2,662)    (4,366)
Earnings/(loss)
 per ordinary
 share
 -- basic........            (0.00)         --             (0.03)    (0.04)     0.01             0.01              --         --
 -- diluted......            (0.00)         --             (0.03)    (0.04)     0.01             0.01              --         --
Weighted average
 ordinary shares
 outstanding
 -- basic........          112,660          --           112,660   112,660    28,982           28,982              --         --
 -- diluted......          112,660          --           112,660   112,660    30,108           30,108              --         --
Pro forma
 information
 based on
 exchange ratio
 of 3.4122(10)
Pro forma
 earnings/(loss)
 per ordinary
 share
 -- basic........                                                                                                (0.01)     (0.02)
 -- diluted......                                                                                                (0.01)     (0.02)
Pro forma
 weighted average
 ordinary shares
 outstanding
 -- basic........                                                                                              211,552    211,552
 -- diluted......                                                                                              211,552    211,552
Pro forma
 earnings/(loss)
 per ADS
 -- basic........                                                                                                (0.04)     (0.06)
 -- diluted......                                                                                                (0.04)     (0.06)
Pro forma
 information
 based on
 exchange ratio
 of 3.8407(10)
Pro forma
 earnings/(loss)
 per ordinary
 share
 -- basic........                                                                                                (0.01)     (0.02)
 -- diluted......                                                                                                (0.01)     (0.02)
Pro forma
 weighted average
 ordinary shares
 outstanding
 -- basic........                                                                                              223,971    223,971
 -- diluted......                                                                                              223,971    223,971
Pro forma
 earnings/(loss)
 per ADS
 -- basic........                                                                                                (0.04)     (0.06)
 -- diluted......                                                                                                (0.04)     (0.06)
Pro forma
 information
 based on
 exchange ratio
 of 3.1280(10)
Pro forma
 earnings/(loss)
 per ordinary
 share
 -- basic........                                                                                                (0.01)     (0.02)
 -- diluted......                                                                                                (0.01)     (0.02)
Pro forma
 weighted average
 ordinary shares
 outstanding
 -- basic........                                                                                              203,316    203,316
 -- diluted......                                                                                              203,316    203,316
Pro forma
 earnings/(loss)
 per ADS
 -- basic........                                                                                                (0.04)     (0.06)
 -- diluted......                                                                                                (0.04)     (0.06)
</TABLE>

                                       22
<PAGE>


            Unaudited Pro Forma Combined Condensed Income Statement

                            Year Ended June 30, 1997

<TABLE>
<CAPTION>
                                          Shire                                     Roberts            Shire Roberts Pro Forma
                   -------------------------------------------------------  -------------------------  -------------------------
                                    Adjustments                    U.S.       U.S.                                       U.S.
                      U.K.GAAP          (1)        U.S. GAAP      GAAP(2)    GAAP(3)    U.S. GAAP(4)    U.S. GAAP(5)    GAAP(6)
                   --------------  ------------  --------------  ---------  ---------  --------------  --------------  ---------
                                       (in thousands, except per ordinary share and per ADS amounts)
<S>                <C>             <C>           <C>             <C>        <C>        <C>             <C>             <C>
Total revenue....  (Pounds)23,072  (Pounds) --   (Pounds)23,072  $  37,146  $ 110,696  (Pounds)68,755  (Pounds)91,827  $ 147,842
Operating ex-
 penses..........         (24,471)      (50,886)        (75,357)  (121,325)  (151,633)        (94,182)       (169,539)  (272,958)
Operating
 income/(loss)...          (1,399)      (50,886)        (52,285)   (84,179)   (40,937)        (25,427)        (77,712)  (125,116)
Interest income..           1,278           --            1,278      2,058      4,810           2,988           4,266      6,868
Interest ex-
 penses..........             (25)          --              (25)       (40)    (1,011)           (628)           (653)    (1,051)
Other, net.......             --            --              --         --          90              56              56         90
Income/(loss)
 from continuing
 operations
 before income
 taxes...........            (146)      (50,886)        (51,032)   (82,161)   (37,048)        (23,011)        (74,073)  (119,209)
Income taxes.....             --            794             794      1,278     10,937           6,793           7,587     12,215
Income/(loss)
 from continuing
 operations......            (146)      (50,092)        (50,238)   (80,883)   (26,111)        (16,218)        (66,456)  (106,994)
Earnings/(loss)
 per ordinary
 share
 -- basic........           (0.00)          --            (0.75)     (1.20)     (1.07)          (0.66)            --         --
 -- diluted......           (0.00)          --            (0.75)     (1.20)     (1.07)          (0.66)            --         --
Weighted average
 ordinary shares
 outstanding
 -- basic........          67,153           --           67,153     67,153     24,499          24,499             --         --
 -- diluted......          67,153           --           67,153     67,153     24,499          24,499             --         --
Pro forma infor-
 mation based on
 exchange
 ratio of
 3.4122(10)
Pro forma
 earnings/(loss)
 per ordinary
 share
 -- basic........                                                                                               (0.44)     (0.71)
 -- diluted......                                                                                               (0.44)     (0.71)
Pro forma
 weighted average
 ordinary shares
 outstanding
 -- basic........                                                                                             150,748    150,748
 -- diluted......                                                                                             150,748    150,748
Pro forma
 earnings/(loss)
 per ADS
 -- basic........                                                                                               (1.32)     (2.13)
 -- diluted......                                                                                               (1.32)     (2.13)
Pro forma infor-
 mation based on
 exchange
 ratio of
 3.8407(10)
Pro forma
 earnings/(loss)
 per ordinary
 share
 -- basic........                                                                                               (0.41)     (0.66)
 -- diluted......                                                                                               (0.41)     (0.66)
Pro forma
 weighted average
 ordinary shares
 outstanding
 -- basic........                                                                                             161,246    161,246
 -- diluted......                                                                                             161,246    161,246
Pro forma
 earnings/(loss)
 per ADS
 -- basic........                                                                                               (1.24)     (1.99)
 -- diluted......                                                                                               (1.24)     (1.99)
Pro forma infor-
 mation based on
 exchange
 ratio of 3.1280
Pro forma
 earnings/(loss)
 per ordinary
 share
 -- basic........                                                                                               (0.46)     (0.74)
 -- diluted......                                                                                               (0.46)     (0.74)
Pro forma
 weighted average
 ordinary shares
 outstanding
 -- basic........                                                                                             143,786    143,786
 -- diluted......                                                                                             143,786    143,786
Pro forma
 earnings/(loss)
 per ADS
 -- basic........                                                                                               (1.39)     (2.23)
 -- diluted......                                                                                               (1.39)     (2.23)
</TABLE>

                                       23
<PAGE>

            Unaudited Pro Forma Combined Condensed Income Statement

                            Year Ended June 30, 1996

<TABLE>
<CAPTION>
                                             Shire                                            Roberts
                   -------------------------------------------------------------- ---------------------------------
                                   Adjustments
                     U.K. GAAP         (1)          U.S. GAAP       U.S. GAAP(2)  U.S. GAAP(3)      U.S. GAAP(4)
                   --------------  -----------  ------------------  ------------- -------------  ------------------
                                                 (in thousands, except per ordinary share and per ADS amounts)
<S>                <C>             <C>          <C>                 <C>           <C>            <C>
Total revenue....  (Pounds)21,043  (Pounds)--   (Pounds)    21,043  $     32,617  $     110,920  (Pounds)    71,561
Operating
 expenses........         (18,474)     (14,995)            (33,469)      (51,877)      (115,217)            (74,334)
Operating income
 (loss)..........           2,569      (14,995)            (12,426)      (19,260)        (4,297)             (2,772)
Interest income..             606          --                  606           939          1,875               1,210
Interest
 expenses........            (453)         --                 (453)         (702)        (3,007)             (1,940)
Other, net.......             --           --                  --            --              36                  23
Income (loss)
 from continuing
 operations
 before income
 taxes...........           2,722      (14,995)            (12,273)      (19,023)        (5,393)             (3,479)
Income taxes.....            (167)         251                  84           130            581                 375
Income (loss)
 from continuing
 operations......           2,555      (14,744)            (12,189)      (18,893)        (4,812)             (3,104)
Earnings/(loss)
 per ordinary
 share
 -- basic........            0.06          --                (0.28)        (0.43)         (0.26)              (0.17)
 -- diluted......            0.06          --                (0.28)        (0.43)         (0.26)              (0.17)
Weighted average
 ordinary shares
 outstanding
 -- basic........          44,154          --               44,154        44,154         18,672              18,672
 -- diluted......          45,208          --               44,154        44,154         18,672              18,672
Pro forma
 information
 based on
 exchange ratio
 of 3.4122(10)
Pro forma
 earnings/(loss)
 per ordinary
 share
 -- basic........
 -- diluted......
 Pro forma
  weighted
  average
  ordinary shares
  outstanding
 -- basic........
 -- diluted......
Pro forma
 earnings/(loss)
 per ADS
 -- basic........
 -- diluted......
Pro forma
 information
 based on
 exchange ratio
 of 3.8407(10)
Pro forma
 earnings/(loss)
 per ordinary
 share
 -- basic........
 -- diluted......
Pro forma
 weighted average
 ordinary shares
 outstanding
 -- basic........
 -- diluted......
Pro forma
 earnings/(loss)
 per ADS
 -- basic........
 -- diluted......
Pro forma
 information
 based on
 exchange ratio
 of 3.1280
Pro forma
 earnings/(loss)
 per ordinary
 share
 -- basic........
 -- diluted......
Pro forma
 weighted average
 ordinary shares
 outstanding
 -- basic........
 -- diluted......
Pro forma
 earnings/(loss)
 per ADS
 -- basic........
 -- diluted......
<CAPTION>
                   Shire Roberts Pro Forma
                   --------------------------
                                     U.S.
                    U.S. GAAP(5)    GAAP(6)
                   --------------- ----------
<S>                <C>             <C>
Total revenue....  (Pounds)92,604  $ 143,537
Operating
 expenses........        (107,803)  (167,094)
Operating income
 (loss)..........         (15,199)   (23,557)
Interest income..           1,816      2,814
Interest
 expenses........          (2,393)    (3,709)
Other, net.......              23         36
Income (loss)
 from continuing
 operations
 before income
 taxes...........         (15,753)   (24,416)
Income taxes.....             459        711
Income (loss)
 from continuing
 operations......         (15,294)   (23,705)
Earnings/(loss)
 per ordinary
 share
 -- basic........             --         --
 -- diluted......             --         --
Weighted average
 ordinary shares
 outstanding
 -- basic........             --         --
 -- diluted......             --         --
Pro forma
 information
 based on
 exchange ratio
 of 3.4122(10)
Pro forma
 earnings/(loss)
 per ordinary
 share
 -- basic........           (0.14)     (0.22)
 -- diluted......           (0.14)     (0.22)
 Pro forma
  weighted
  average
  ordinary shares
  outstanding
 -- basic........         107,867    107,867
 -- diluted......         107,867    107,867
Pro forma
 earnings/(loss)
 per ADS
 -- basic........           (0.43)     (0.66)
 -- diluted......           (0.43)     (0.66)
Pro forma
 information
 based on
 exchange ratio
 of 3.8407(10)
Pro forma
 earnings/(loss)
 per ordinary
 share
 -- basic........           (0.13)     (0.20)
 -- diluted......           (0.13)     (0.20)
Pro forma
 weighted average
 ordinary shares
 outstanding
 -- basic........         115,868    115,868
 -- diluted......         115,868    115,868
Pro forma
 earnings/(loss)
 per ADS
 -- basic........           (0.40)     (0.61)
 -- diluted......           (0.40)     (0.61)
Pro forma
 information
 based on
 exchange ratio
 of 3.1280
Pro forma
 earnings/(loss)
 per ordinary
 share
 -- basic........           (0.15)     (0.23)
 -- diluted......           (0.15)     (0.23)
Pro forma
 weighted average
 ordinary shares
 outstanding
 -- basic........         102,560    102,560
 -- diluted......         102,560    102,560
Pro forma
 earnings/(loss)
 per ADS
 -- basic........           (0.45)     (0.69)
 -- diluted......           (0.45)     (0.69)
</TABLE>

                                       24
<PAGE>


              Unaudited Pro Forma Combined Condensed Balance Sheet

                            As of September 30, 1999

<TABLE>
<CAPTION>
                     U.K. GAAP
                   --------------
<S>                <C>
U.S. GAAP ASSETS
Current assets:
 Cash and current
  investments....  (Pounds)52,508
 Inventory, net..           7,612
 Accounts
  receivable,
  net............          18,685
 Notes
  receivable.....             --
 Other current
  assets.........           2,676
                   --------------
 Total current
  assets.........          81,481
Property and
 equipment, net..           3,423
Intangible
 assets, net.....          14,462
Other assets.....             --
                   --------------
 Totals assets...  (Pounds)99,366
                   ==============
 LIABILITIES AND
   SHAREHOLDERS
      EQUITY
Current
 liabilities:
Current
 installments of
 long term debt..  (Pounds) 5,354
Accounts payable
 and accrued
 expenses........          17,672
Taxes, other than
 income taxes....           2,236
Income taxes
 payable.........             197
Other current
 liabilities.....             969
                   --------------
 Total current
  liabilities....          26,428
Long term debt,
 including
 capital lease
 obligations.....           1,825
Other
 liabilities.....             877
Shareholders'
 equity..........          70,236
                   --------------
 Total
  liabilities and
  shareholders'
  equity.........  (Pounds)99,366
                   ==============
<CAPTION>
                             Shire                                   Roberts                 Shire Roberts Pro Forma
                   ----------------------------------------- ------------------------ --------------------------------------
                                                      U.S.     U.S.                      Merger                       U.S.
                   Adjustments (7)     U.S. GAAP    GAAP(8)    GAAP    U.S. GAAP(9)   Adjustment(9)    U.S. GAAP      GAAP
                   ---------------- --------------- -------- -------- --------------- ------------- --------------- --------
                                 (in thousands, except per ordinary share and per ADS amounts)
<S>                <C>              <C>             <C>      <C>      <C>             <C>           <C>             <C>
U.S. GAAP ASSETS
Current assets:
 Cash and current
  investments....  (Pounds)    --   (Pounds) 52,508 $ 86,113 $ 63,323 (Pounds) 38,612  (Pounds)--   (Pounds) 91,120 $149,436
 Inventory, net..              --             7,612   12,484   29,186          17,796          --            25,408   41,670
 Accounts
  receivable,
  net............              --            18,685   30,643   41,552          25,337          --            44,022   72,195
 Notes
  receivable.....              --               --       --     6,259           3,816          --             3,816    6,259
 Other current
  assets.........            7,402           10,078   16,528   12,174           7,423          --            17,501   28,702
                   ---------------- --------------- -------- -------- --------------- ------------- --------------- --------
 Total current
  assets.........            7,402           88,883  145,768  152,494          92,984          --           181,867  298,262
Property and
 equipment, net..              --             3,423    5,614   37,049          22,591          --            26,014   42,663
Intangible
 assets, net.....          119,964          134,426  220,459  348,761         212,659          --           347,085  569,220
Other assets.....           11,943           11,943   19,586   12,683           7,734          --            19,677   32,269
                   ---------------- --------------- -------- -------- --------------- ------------- --------------- --------
 Totals assets...  (Pounds)139,309  (Pounds)238,675 $391,427 $550,987 (Pounds)335,968  (Pounds)--   (Pounds)574,643 $942,414
                   ================ =============== ======== ======== =============== ============= =============== ========
 LIABILITIES AND
   SHAREHOLDERS
      EQUITY
Current
 liabilities:
Current
 installments of
 long term debt..  (Pounds)    --   (Pounds)  5,354 $  8,781 $  7,899 (Pounds)  4,816  (Pounds)--   (Pounds) 10,170 $ 16,680
Accounts payable
 and accrued
 expenses........              --            17,672   28,982   16,895          10,302       10,000           37,974   62,277
Taxes, other than
 income taxes....              --             2,236    3,667      --              --           --             2,236    3,667
Income taxes
 payable.........              --               197      323      --              --           --               197      323
Other current
 liabilities.....              --               969    1,589   35,825          21,845                        22,814   37,414
                   ---------------- --------------- -------- -------- --------------- ------------- --------------- --------
 Total current
  liabilities....              --            26,428   43,342   60,619          36,963       10,000           73,391  120,361
Long term debt,
 including
 capital lease
 obligations.....              --             1,825    2,993  122,188          74,505          --            76,330  125,181
Other
 liabilities.....              --               877    1,438      840             512          --             1,389    2,278
Shareholders'
 equity..........          139,309          209,545  343,654  367,340         223,988      (10,000)         423,533  694,594
                   ---------------- --------------- -------- -------- --------------- ------------- --------------- --------
 Total
  liabilities and
  shareholders'
  equity.........  (Pounds)139,309  (Pounds)238,675 $391,427 $550,987 (Pounds)335,968  (Pounds)--   (Pounds)574,643 $942,414
                   ================ =============== ======== ======== =============== ============= =============== ========
</TABLE>

                                       25
<PAGE>


Notes

1. Adjustments reflecting differences between U.S. GAAP and U.K. GAAP:

<TABLE>
<CAPTION>
                             Year ended     Year ended    Six months ended   Year ended    Nine months ended
                            June 30, 1996  June 30, 1997   Dec. 31, 1997   Dec. 31, 1998   September 30, 1999
                            -------------  -------------  ---------------- --------------  ------------------
   <S>                      <C>            <C>            <C>              <C>             <C>
   Amortization of
    goodwill............... (Pounds)(167)  (Pounds)(220)   (Pounds)(2,334) (Pounds)(6,709)   (Pounds)(5,103)
   Write off of in process
    research and
    development............      (14,728)       (50,626)              --              --                --
   Recognition of deferred
    tax asset..............          251            794             1,222           7,765             1,771
   Share option
    compensation costs.....         (100)           (40)           (1,365)         (3,313)           (6,380)
   Tax benefits of share
    option deductions......          --             --                --           (1,811)           (2,017)
                            ------------   ------------    --------------  --------------    --------------
     Total.................      (14,744)       (50,092)           (2,477)         (4,068)          (11,729)
</TABLE>

  The following represent adjustments made to the Shire historical financial
  statements to convert them from U.K. GAAP to U.S. GAAP:

  (a) adjustment to record amortization charge on goodwill associated with
      previous acquisitions of Shire, namely Shire Pharmaceutical Contracts
      Ltd., Shire Laboratories Inc. and Shire Richwood Inc. Goodwill is being
      amortized on a straight line basis over its estimated useful life which
      ranges from 5 to 30 years. The weighted average amortisable life of
      goodwill at September 30, 1999 was 21 years. (See note 7a).

  (b)  adjustment for the write off of that portion of the purchase price of
       the acquisition of Shire Pharmaceutical Contracts Limited, Shire
       Laboratories Inc. and Shire Richwood Inc. allocated to in process
       research and development where technological feasibility has not yet
       been established and for which there were no alternative future uses.

  (c) adjustment to recognize deferred tax assets which arise primarily from
      net operating loss carryforwards;

  (d) adjustment to record stock option compensation costs based on APB
      Opinion 25. See "Adoption of U.S. GAAP for Accounting Purposes."

    (e) adjustment to record the tax benefits of non qualifying stock options.

   See note 24 of Shire's audited financial statements for a discussion of
these items.

2. Translation of pounds sterling into U.S. dollars has been made at the
   following rates based upon the average noon buying rates for the period.
   Such translation is based on generally accepted accounting principles for
   foreign currency translations.

<TABLE>
<CAPTION>
                             Year ended    Year ended   Six months ended  Year ended   Nine months ended
                            June 30, 1996 June 30, 1997  Dec. 31, 1997   Dec. 31, 1998 September 30, 1999
                            ------------- ------------- ---------------- ------------- ------------------
   <S>                      <C>           <C>           <C>              <C>           <C>
   U.S. dollars per
    (Pounds)1.00...........     1.55          1.61            1.64           1.66             1.62
</TABLE>

3. To present the results of Roberts for the years ended June 30, 1997 and
   1996, and for the six month period ended December 31, 1997 the quarterly
   results on Form 10-Q were combined. There were no periods excluded from or
   included more than once in the recast financial statements.

                                       26
<PAGE>

4. Translation of U.S. dollars into pounds sterling has been made at the
   following rates based upon the average noon buying rates for the period.
   Such translation is based on generally accepted accounting principles for
   foreign currency translations.

<TABLE>
<CAPTION>
                             Year ended    Year ended   Six months ended  Year ended   Nine months ended
                            June 30, 1996 June 30, 1997  Dec. 31, 1997   Dec. 31, 1998 September 30, 1999
                            ------------- ------------- ---------------- ------------- ------------------
   <S>                      <C>           <C>           <C>              <C>           <C>
   Pounds sterling per
    $1.00..................     0.65          0.62            0.61           0.60             0.62
</TABLE>

 5. Represents total of Shire and Roberts U.S. GAAP income statements stated in
    pounds sterling.

 6. Represents total of Shire and Roberts U.S. GAAP income statements stated in
    U.S. dollars.

 7. Reflects adjustment:
<TABLE>
<CAPTION>
                                                            September 30, 1999
                                                            ------------------
   <S>                                                      <C>
   Capitalization of goodwill arising on acquisitions, net
    of amortization.......................................       119,964
   Recognition of deferred tax asset......................        19,345
                                                                 -------
                                                                 139,309
</TABLE>

  (a) adjustment to record goodwill and related accumulated amortization
      associated with previous acquisitions of Shire, namely Shire
      Pharmaceutical Contracts Ltd., Shire Laboratories Inc. and Shire
      Richwood Inc. Goodwill is being amortized on a straight line basis over
      its estimated useful life which ranges from 5 to 30 years;

  Capitalization of goodwill arising on acquisitions, net of amortization:

<TABLE>
<CAPTION>
                                                 Goodwill
                            Completed Assembled  and other    Deferred
                            products  workforce intangibles consideration  Total
                            --------- --------- ----------- ------------- -------
   <S>                      <C>       <C>       <C>         <C>           <C>
   As at September 30,
    1999...................  100,433    1,324     12,620        5,587     119,964
</TABLE>

  The weighted average amortisable life of goodwill at September 30, 1999 was
     21 years.

  (b) adjustment to recognize deferred tax assets which arise primarily from
      net operating loss carryforwards.

 8. Translation of pounds sterling into U.S. dollars has been made at the rate
    of (Pounds)1.00 = $1.64 (the noon buying rate on September 30, 1999) based
    on generally accepted accounting principles for foreign currency
    translations. Translation of U.S. dollars into pounds sterling has been
    made at the rate of $1.00 = (Pounds)0.61.

 9. The unaudited pro forma combined income statements do not reflect expenses
    expected to be incurred by Shire and Roberts directly related to the merger
    as these costs will not have a continuing impact on the financial results.
    These expenses, consisting primarily of professional fees and distributing
    proxy materials are estimated at $16.4 million and will be charged as an
    operating expense upon consummation of the merger.

10. Pro forma weighted average ordinary shares have been calculated using the
    exchange ratios of 3.4122, 3.8407 and 3.1280 which are the mid, highest and
    lowest number of ordinary shares that can be issued for each Roberts share
    under the terms of the merger agreement.

  Earnings per share information is presented under the 3 scenarios to
  demonstrate the effect of the exchange ratio on the pro forma results.

                                       27
<PAGE>

                           Comparative Per Share Data

   The following table presents certain historical per share data for Shire and
Roberts and unaudited pro forma and equivalent pro forma combined per share
data to reflect the consummation of the merger based upon the historical
financial results of Shire and Roberts presented under U.S. GAAP and the
conversion of each Roberts share into 1.1374 ADSs (the exchange ratio as of
July 23, 1999). The pro forma data are not necessarily indicative of actual or
future operating results or of the financial position that would have occurred
or will occur upon consummation of the merger. The data presented below should
be read in conjunction with the separate historical consolidated financial
statements of Shire and Roberts which are incorporated in this Prospectus-Proxy
Statement by reference.

<TABLE>
<CAPTION>
                                                 Nine Months Ended September 30, 1999
                          ---------------------------------------------------------------------------------------
                                                                                             Roberts Equivalent
                            Shire Historical      Roberts Historical  Pro Forma Combined        Pro Forma(1)
                          ----------------------  ------------------ ---------------------  ---------------------
                                         Note 2            Note 3
<S>                       <C>            <C>      <C>   <C>          <C>            <C>     <C>            <C>
Basic earnings per
 ordinary share.........   (Pounds)0.04    $0.06  $0.62 (Pounds)0.38  (Pounds)0.07   $0.12   (Pounds)0.24   $0.39
Diluted earnings per
 ordinary share.........           0.04     0.06   0.61         0.38          0.07    0.11           0.23    0.38
Basic earnings per ADS..           0.12     0.19   1.86         1.15          0.21    0.35           0.73    1.19
Diluted earnings per
 ADS....................           0.11     0.18   1.83         1.13          0.21    0.33           0.70    1.13
Book value per ordinary
 share (4)..............           1.46     2.39  11.38         7.06          1.67    2.74           5.69    9.34
Book value per ADS......           4.38     7.18  34.14        21.17          5.00    8.21          17.08   28.01
<CAPTION>
                                                     Year Ended December 31, 1998
                          ---------------------------------------------------------------------------------------
                                                                                             Roberts Equivalent
                            Shire Historical      Roberts Historical  Pro Forma Combined        Pro Forma(1)
                          ----------------------  ------------------ ---------------------  ---------------------
                                         Note 2            Note 3
<S>                       <C>            <C>      <C>   <C>          <C>            <C>     <C>            <C>
Basic earnings per
 ordinary share.........   (Pounds)0.02    $0.03  $0.54 (Pounds)0.33  (Pounds)0.05   $0.08   (Pounds)0.17   $0.27
Diluted earnings per
 ordinary share.........           0.02     0.03   0.53         0.32          0.05    0.08           0.17    0.27
Basic earnings per ADS..           0.05     0.08   1.62         0.98          0.15    0.25           0.52    0.85
Diluted earnings per
 ADS....................           0.05     0.08   1.60         0.96          0.15    0.24           0.50    0.83
Book value per ordinary
 share (4)..............           1.37     2.27  10.86         6.52          1.56    2.58           5.31    8.82
Book value per ADS......           4.11     6.82  32.58        19.55          4.67    7.75          15.94   26.46
<CAPTION>
                                                  Six Months Ended December 31, 1997
                          ---------------------------------------------------------------------------------------
                                                                                             Roberts Equivalent
                            Shire Historical      Roberts Historical  Pro Forma Combined        Pro Forma(1)
                          ----------------------  ------------------ ---------------------  ---------------------
                                         Note 2            Note 3
<S>                       <C>            <C>      <C>   <C>          <C>            <C>     <C>            <C>
Basic earnings/(loss)
 per ordinary share.....  (Pounds)(0.03) $ (0.04) $0.01 (Pounds)0.01 (Pounds)(0.01) $(0.02) (Pounds)(0.04) $(0.07)
Diluted earnings/(loss)
 per ordinary share.....          (0.03)   (0.04)  0.01         0.01         (0.01)  (0.02)         (0.04)  (0.07)
Basic earnings/(loss)
 per ADS................          (0.08)   (0.12)  0.03         0.02         (0.04)  (0.06)         (0.13)  (0.21)
Diluted earnings/(loss)
 per ADS................          (0.08)   (0.12)  0.03         0.02         (0.04)  (0.06)         (0.13)  (0.21)
</TABLE>


                                       28
<PAGE>

<TABLE>
<CAPTION>
                                                       Year Ended June 30, 1997
                          ------------------------------------------------------------------------------------------
                                                                                                Roberts Equivalent
                            Shire Historical      Roberts Historical     Pro Forma Combined        Pro Forma(1)
                          ---------------------  ---------------------  ---------------------  ---------------------
                                         Note 2             Note 3
<S>                       <C>            <C>     <C>     <C>            <C>            <C>     <C>            <C>
Basic earnings/(loss)
 per ordinary share.....  (Pounds)(0.75) $(1.20) $(1.07) (Pounds)(0.66) (Pounds)(0.44) $(0.71) (Pounds)(1.50) $(2.42)
Diluted earnings/(loss)
 per ordinary share.....          (0.75)  (1.20)  (1.07)         (0.66)         (0.44)  (0.71)         (1.50)  (2.42)
Basic earnings/(loss)
 per ADS................          (2.24)  (3.61)  (3.20)         (1.99)         (1.32)  (2.13)         (4.50)  (7.26)
Diluted earnings/(loss)
 per ADS................          (2.24)  (3.61)  (3.20)         (1.99)         (1.32)  (2.13)         (4.50)  (7.26)
<CAPTION>
                                                       Year Ended June 30, 1996
                          ------------------------------------------------------------------------------------------
                                                                                                Roberts Equivalent
                            Shire Historical      Roberts Historical     Pro Forma Combined        Pro Forma(1)
                          ---------------------  ---------------------  ---------------------  ---------------------
                                         Note 2             Note 3
<S>                       <C>            <C>     <C>     <C>            <C>            <C>     <C>            <C>
Basic earnings per
 ordinary share.........  (Pounds)(0.28) $(0.43) $(0.26) (Pounds)(0.17) (Pounds)(0.14) $(0.22) (Pounds)(0.48) $(0.75)
Diluted earnings per
 ordinary share.........          (0.28)  (0.43)  (0.26)         (0.17)         (0.14)  (0.22)         (0.48)  (0.75)
Basic earnings per ADS..          (0.83)  (1.29)  (0.77)         (0.50)         (0.43)  (0.66)         (1.47)  (2.25)
Diluted earnings per
 ADS....................          (0.83)  (1.29)  (0.77)         (0.50)         (0.43)  (0.66)         (1.47)  (2.25)
</TABLE>

Notes

1. The equivalent pro forma per share amounts were calculated by multiplying
   pro forma income per share and pro forma book value per share by the
   exchange ratio of 3.4122.

2. Translation of pounds sterling into U.S. dollars has been made at the
   following rates based upon the average noon buying rates for the period.
   Such translation is based on generally accepted accounting principles for
   foreign currency translations.

<TABLE>
<CAPTION>
                             Year ended    Year ended   Six months ended  Year ended   Nine months ended
                            June 30, 1996 June 30, 1997  Dec. 31, 1997   Dec. 31, 1998 September 30, 1999
                            ------------- ------------- ---------------- ------------- ------------------
   <S>                      <C>           <C>           <C>              <C>           <C>
   U.S. dollars per
    (Pounds)1.00...........     1.55          1.61            1.64           1.66             1.62
</TABLE>

3. Translation of U.S. dollars into pounds sterling has been made at the
   following rates based upon the average noon buying rates for the period.
   Such translation is based on generally accepted accounting principles for
   foreign currency translations.

<TABLE>
<CAPTION>
                             Year ended    Year ended   Six months ended  Year ended   Nine months ended
                            June 30, 1996 June 30, 1997  Dec. 31, 1997   Dec. 31, 1998 September 30, 1999
                            ------------- ------------- ---------------- ------------- ------------------
   <S>                      <C>           <C>           <C>              <C>           <C>
   Pounds sterling per
    $1.00..................     0.65          0.62            0.61           0.60             0.62
</TABLE>

4. Represents the amount of shareholders' equity, stated based on U.S. GAAP,
   divided by the number of shares outstanding at each period end.

   The number of shares assumed to be outstanding, on a pro forma basis using
   the exchange ratio of 3.4122, at each period end are as follows:

<TABLE>
     <S>                                                           <C>
     At December 31, 1998                                          249,925,000
     At September 30, 1999                                         253,879,000
</TABLE>

                                      29
<PAGE>

                      Comparative Market Price Information

   Shire ADSs are listed and traded on Nasdaq under the symbol "SHPGY." Each
ADS represents three ordinary shares. Roberts shares are listed and traded on
Amex under the symbol "RPC." Shire ordinary shares are listed and traded on the
London Stock Exchange Limited under the symbol "SHP.L." The following table
presents the per share closing market prices for the ADSs and Roberts shares on
Nasdaq and the Amex, respectively, and the closing mid-market quotation for the
ordinary shares as quoted in the Daily Official List of the LSE, for the
periods indicated.

<TABLE>
<CAPTION>
                                                                     Roberts
                        Shire ADSs        Shire Ordinary Shares      Shares
                       ---------------- ------------------------- -------------
                        High      Low       High         Low       High   Low
                       ------    ------ ------------ ------------ ------ ------
<S>                    <C>       <C>    <C>          <C>          <C>    <C>
1999
3rd Quarter ..........
2nd Quarter........... $26.00    $18.88 (Pounds)5.28 (Pounds)3.96 $24.00 $17.00
1st Quarter...........  25.50     19.13         5.17         3.74  26.06  18.50
1998
4th Quarter...........  22.50     18.63         4.35         3.46  24.63  17.25
3rd Quarter...........  27.81     16.56         5.41         2.94  24.31  16.63
2nd Quarter...........  23.00     19.00         4.44         3.80  23.00  13.25
1st Quarter...........  21.44     20.00         4.10         2.87  14.25   9.69
1997
4th Quarter...........    -- (1)    --          2.88         2.60  11.75   9.56
3rd Quarter...........    --        --          2.84         2.35  12.75   9.88
2nd Quarter...........    --        --          2.37         2.17  13.50  10.19
1st Quarter...........    --        --          2.39         2.17  14.50  11.38
</TABLE>
- --------
(1) The initial offering of ADSs was in March 1998.

   On July 23, 1999, the last trading date before public announcement of the
execution of the merger agreement, the closing price per ADS was $27.00, the
closing price per Roberts share was $25.00 and the closing mid-market quotation
per ordinary share was 565p. On   , 1999, such per share prices were $  , $
and  p, respectively.

   On October 14, 1999, there were approximately 9,597,822 issued and
outstanding ADSs and 143,628,836 ordinary shares in issue, including ordinary
shares underlying ADSs. On that date, approximately 100% of the ADSs were held
in the U.S. by 27 record holders, one of which is the Depository Trust Company.
On October 15, 1999, there were approximately 31,997,043 issued and outstanding
shares of Roberts common stock, of which 99.9% were held in the U.S. by 838
record holders.

                                Dividend Policy

   Historically, Shire has not paid any dividends. Shire does not anticipate
paying any dividends on ordinary shares, or indirectly on ADSs, in the
foreseeable future. As a matter of English law, Shire may pay dividends only
out of its distributable profits, which are its accumulated realized profits
under U.K. GAAP, so far as not previously utilized by distribution or
capitalization, less its accumulated, realized losses, so far as not previously
written off in a reduction or reorganization of capital duly made. As of
December 31, 1998, Shire had an accumulated deficit of (Pounds)1.6 million.
Future dividend policy will be dependent upon Shire's distributable profits,
the financial condition of Shire, the terms of any then existing debt
facilities and other relevant factors existing at that time.

   Roberts has not paid any cash dividends on Roberts shares in the past and it
is unlikely that it will pay any dividends on Roberts shares in the foreseeable
future.


                                       30
<PAGE>

                                  RISK FACTORS

   You should carefully consider the following risk factors in evaluating
whether to vote FOR or AGAINST the approval and adoption of the merger
agreement.

The following are risks that relate to the merger.

   If Shire and Roberts do not successfully integrate their operations, the
merger may not benefit us or our shareholders. The combination of Shire and
Roberts involves the integration of separate companies that have previously
operated independently. If the integration is not completed successfully or
takes longer than planned, the anticipated benefits of the merger may be lost
or delayed. We may have difficulties integrating our sales forces,
manufacturing facilities and infrastructure in the U.S. In integrating the
operations of Roberts, Shire may encounter difficulties or experience the loss
of key employees, customers or suppliers. In addition, Shire and Roberts must
successfully integrate the operations and management of the two companies to
achieve the potential benefits that were a factor in the Shire board's and the
Roberts board's approving the merger.

   Because the exchange ratio is based on a range of trading prices, the value
you will receive for your Roberts shares can not be determined today. The
exchange ratio establishing the number of ordinary shares (or ADSs) you receive
in the merger is fixed in the event the average ADS trading price at the close
of the market for the 15 trading days ending the third trading day before the
merger is below $21.09, between $23.73 and $29.01, or above $31.65. This means
that a decrease in the value of the ADSs within these ranges will decrease the
value of the consideration you receive for your Roberts shares. For a tabular
presentation of the hypothetical values you would receive for each Roberts
share you own based on various ADS trading values see "The Merger Agreement--
The Exchange Ratio." You should also note that neither Shire nor Roberts can
terminate the merger agreement as a result of these fluctuations.

   The trading value of the ADSs will vary between the date of this Prospectus-
Proxy Statement and the date of the completion of the merger. Because the
merger may occur at a date later than the special meeting, the share prices at
the time of the special meeting may not be indicative of the consideration you
will receive at the closing of the merger.

   Persons affiliated with Roberts have interests that may conflict with the
interests of Roberts shareholders in the merger. Some members of Roberts'
management have interests in the merger that are different from or in addition
to your interests as a Roberts shareholder. As a result, these individuals may
have interests different from your own. Specifically:

  . some of Roberts' directors will be appointed directors of Shire after the
     merger;

  .  six senior executives of Roberts will be entitled under their employment
     agreements to receive, if their employment is terminated after the
     merger in circumstances described in their employment agreements,
     severance payments equal to three or four times their salary, plus
     additional payments;

  .  a number of other executives, if their employment is terminated after
     the merger, will be entitled to receive a severance payment equal to one
     year's salary plus other payments;

  .  under Roberts' Change of Control Severance Plan, any employee whose
     employment is terminated "without cause" after the merger will be
     entitled to a severance payment;

  .  options granted under the 1996 Equity Incentive Plan will vest and
     become exercisable after the merger;

  .  under the terms of Roberts' SERP and as a result of the merger, the plan
     participants will become fully vested and Roberts will be required to
     credit each of the plan participants with 10 years of service with
     Roberts and fund the SERP in an amount sufficient to pay all benefits
     under the plan;

  .  when the merger is completed, John T. Spitznagel, President and Chief
     Executive Officer of Roberts, will resign his position with Roberts and
     become entitled to severance benefits under his employment

                                       31
<PAGE>

   agreement. Mr. Spitznagel and Shire will enter into a consulting agreement
   for a term of 42 months for a total consideration of $940,000 per annum;
   and

  .  Shire has agreed to indemnify each of Roberts' current directors and
     officers against losses and claims arising in connection with their
     actions as a director or officer prior to the merger and to provide
     insurance for up to six years.

We have described the interests of these persons in more detail under the
heading "Interests in the Merger of Persons Affiliated with Roberts."

   Termination fees and an option agreement could make an alternative
transaction more difficult or expensive. Shire or Roberts must pay to the
other a termination fee of $30 million if the merger agreement terminates
under specified circumstances. Shire and Roberts have also entered into an
option agreement which provides Shire with the right to acquire up to 19.9% of
Roberts' outstanding common stock under specified conditions. The termination
fees and the option agreement could deter interested third parties from
entering into an alternative transaction with either Shire or Roberts more
beneficial to shareholders by making such an alternative more difficult or
expensive.

   Roberts' shareholders will experience a reduction in basic and diluted
earnings per share on a pro forma basis. The merger will reduce Roberts' basic
and diluted earnings per share on a pro forma basis for the nine months ended
September 30, 1999, the year ended December 31, 1998 and the six months ended
December 31, 1997. On a historical basis for Roberts, diluted earnings per
share from continuing operations for these periods were $0.61, $0.53 and
$0.01, respectively. On a historical basis for Roberts, basic earnings per
share from continuing operations for these periods were $0.62, $0.54 and $0.01
respectively. On a Roberts equivalent pro forma basis, after giving effect to
the merger, basic earnings per share would have been $0.39, $0.27 and $(0.07)
respectively. On a Robert's equivalent pro forma basis, after giving effect to
the merger, diluted earnings per share would have been $0.38, $0.27 and
$(0.07), respectively. Roberts shareholders will also experience a reduction
in book value per share on a pro forma basis. On a historical basis for
Roberts, book value per share for the periods ended September 30, 1999 and
December 31,1998 was $11.38 and $10.86 respectively. On a Roberts equivalent
pro forma basis, after giving effect to the merger, book value per share would
have been $9.34 at September 30, 1999 and $8.82 at December 31, 1998. The pro
forma earnings per share information contained in this paragraph is the
Roberts pro forma equivalent data which is calculated by multiplying the
pro forma income per share by 3.4122, the exchange ratio as of September 1,
1999. Whether the merger will ultimately add to or reduce Roberts' earnings
per share and book value per share will depend on the actual results achieved
by Shire after the merger when compared to the results that could have been
achieved by Roberts on a stand-alone basis.

The following are risks that relate to the operations of both Roberts and
Shire.

   If we cannot obtain the financing necessary to fund our expansion, we will
not be able to respond to changes in demand from our customers. We anticipate
that our existing capital resources, together with cash expected from
operations and available from bank borrowings, should be sufficient to finance
our current and anticipated operations and working capital requirements for
the next twelve months. However, the acquisition and licensing of products,
the expansion of our sales force, and any expansion or relocation of our
facilities would require substantial capital resources. If adequate funds are
not available, we may be unable to pursue acquisitions, or be forced to
curtail in-licensing or research and development programs. To satisfy our
capital requirements, we may need to raise additional funds through public and
private financings, including equity financings. We may also seek additional
funding through corporate collaborations and other financing arrangements. We
do not know whether adequate funds will be available when needed or on terms
acceptable to us. Alternatively, we may need to obtain funds through
arrangements with future collaborative partners or others that may require us
to relinquish rights to some or all of our technologies or product candidates.
If we are successful in obtaining additional financing, the terms of the
financing may have the effect of diluting the value of ordinary shares and
ADSs.

                                      32
<PAGE>

   We intend to continue to explore acquisitions and if we do not successfully
integrate future acquisitions, we may have products or operations that do not
yield any benefit to us or our shareholders. We intend to pursue product
acquisitions that could complement or expand our business. However, we may not
be able to identify appropriate product acquisition candidates in the future.
If a product acquisition candidate is identified, we do not know if we will be
able to successfully negotiate the terms of that acquisition, finance that
acquisition or integrate an acquired product into our existing business and
products. The negotiation and consummation of potential product acquisitions
could cause diversion of management's time and resources. If we consummate one
or more significant product acquisitions through the issuance of ordinary
shares or ADSs, holders of ordinary shares and ADSs could suffer significant
dilution of their ownership interests.

   If we do not successfully complete our clinical trials, our products will
not receive authorization for manufacture and sale. Before obtaining regulatory
approvals for the commercial sale of each of our products under development, we
must demonstrate through clinical trials that the product is of appropriate
quality, safe and effective for the claimed use. Clinical trials of any product
under development may not demonstrate the quality, safety and efficacy of such
product or will result in an approvable or a marketable product. Our failure to
demonstrate adequately the quality, safety and efficacy of a therapeutic drug
under development would delay or prevent regulatory approval of the product. In
addition, regulatory authorities in Europe or the U.S. (including the U.K.
Medicines Control Agency and the U.S. FDA) may require additional clinical
trials, which could result in increased costs and significant development
delays.

   The completion rate of clinical trials is dependent upon, among other
factors, obtaining adequate clinical supplies and recruiting patients. Delays
in patient enrollment in clinical trials may also result in increased costs and
program delays. Additional delays can occur in instances in which we share
control over the planning and execution of product development with
collaborative partners. We intend to continue to out-license a number of our
products and the clinical development of such out-licensed products would then
be the responsibility of the licensee. We cannot assure you that if clinical
trials are completed, we or our collaborative partners will file for or receive
required authorizations to manufacture and/or market potential products in a
timely manner.

   Because our industry is highly regulated, we must utilize a large amount of
resources before we can produce and sell our products. The clinical
development, manufacture, marketing and sale of pharmaceutical products are
subject to extensive regulation, including separate regulation by each country
in the European Union, the E.U. itself and federal, state and local regulation
in the U.S. Unanticipated legislative and other regulatory actions and
developments concerning various aspects of our operations and products may
adversely affect us. The primary regulatory authorities which regulate our
ability to manufacture and sell pharmaceutical products include the MCA in the
U.K., the FDA and the DEA in the U.S. and the Health Protection Branch of the
Ministry of Health in Canada.

   Drug companies that manufacture or market drugs are required to obtain
regulatory approval before marketing most drug products. Regulatory approval is
generally based on the results of:

  .  preclinical testing;

  .  clinical data;

  .  manufacturing, chemistry and control data; and

  .  bioavailability.

The generation of data is regulated and any generated data are susceptible to
varying interpretations that could delay, limit or prevent regulatory approval.
Required regulatory approvals may not be obtained in a timely manner, if at
all. In addition other regulatory requirements for any such proposed products
may be met. Even if we obtain regulatory approvals, the terms of any product
approval, including labeling, may be more restrictive than we desire and could
affect the marketability of our products.


                                       33
<PAGE>

   Regulatory authorities have the power to:

  .  revoke or suspend approvals of previously approved products;

  .  require the recall of products that fail to meet regulatory
     requirements; and

  .  close manufacturing plants that do not operate in conformity with
     current Good Manufacturing Practices and/or other regulatory
     requirements or approvals.

Such delays or actions could affect our ability to manufacture and sell our
products.

   We face a risk of product liability claims for which we may not have
adequate insurance. Testing, manufacturing, marketing and selling
pharmaceutical products entail a risk of product liability. Our financial
condition and results of operations could be materially adversely affected by
the assertion of a product liability claim for which we do not have adequate
insurance. We could be rendered insolvent if, in the absence of insurance, we
do not have sufficient financial resources to satisfy a liability resulting
from such a claim or to fund the legal defense of such a claim. Product
liability insurance coverage is expensive, difficult to obtain and may not be
available in the future on acceptable terms, or at all. Although Shire carries
primary product liability insurance in the amount of (Pounds)100 million per
claim and (Pounds)100 million in the aggregate on a claims-made basis and
umbrella liability insurance, which can also be used for product liability
claims, in the amount of (Pounds)20 million per claim and (Pounds)20 million in
the aggregate this coverage may not be adequate. This insurance coverage does
not include phentermine, which is not separately insured by Shire in the
current year. See "--Shire is named as a defendant in a large number of
lawsuits involving phentermine." In addition, we do not know if insurance
coverage for present or future products will continue to be available.

   Larger competitors may be able to take our market share by developing
superior or more cost-effective products. The manufacture and sale of
pharmaceuticals is highly competitive. If any products are approved by the FDA
to compete with one of our principal drugs, sales of those drugs will likely
fall. Many of our competitors are large, well-known pharmaceutical, chemical
and health care companies which have considerably greater resources than we do.
Many of our present and potential competitors have research and development
capabilities that may allow them to develop new or improved products that may
compete with our products. Companies with more resources and larger research
and development expenditures have a greater ability to fund research and
clinical trials necessary for regulatory applications. They may also have an
improved likelihood of obtaining approval of drugs competing with those
currently marketed or under development by us. The pharmaceutical industry is
characterized by rapid product development and technological change. Our
pharmaceuticals could be rendered obsolete or uneconomical by the development
of new pharmaceuticals or as the result of either technological advances
affecting the cost of production or marketing or pricing action by one or more
of our competitors.

   Our sales will decline if our products are not accepted by the medical
community. Our ability to sell any pharmaceutical products after the receipt of
regulatory approval will depend in part on the acceptance of those products by
physicians and patients. Unanticipated side effects or unfavorable publicity
concerning any of our products generally or those of our competitors could have
an adverse effect on our ability to maintain and/or obtain regulatory approvals
or successfully market our products. Our future results of operations will also
depend on continued market acceptance of our current products and the lack of
substitutes which are cheaper or more effective.

   Reimbursement policies of third parties may affect the marketing of our
products. Our ability to market our products will depend in part on
reimbursement levels for the cost of the products and related treatment
established by health care providers, including government authorities, private
health insurers and other organizations, such as HMOs and managed care
organizations. Third party payors are increasingly challenging the pricing of
pharmaceutical products and reviewing their reimbursement practices. In
addition, the purchase

                                       34
<PAGE>

of pharmaceutical products could be significantly influenced by the following,
which would result in lower prices and a reduced demand for our products:

  .  the trend toward managed health care in the U.S.;

  .  the growth of organizations such as HMOs and MCOs;

  .  legislative proposals to reform health care and government insurance
     programs; and

  .  price controls and non-reimbursement of new and highly priced medicines
     for which the economic and therapeutic rationales are not established.

These cost containment measures and health care reform could affect our ability
to sell our products.

   The reimbursement status of a newly approved pharmaceutical product may be
uncertain. Reimbursement might not be available for some of our products.
Reimbursement for a product, if granted, may not be maintained. Limits placed
on reimbursement could reduce the demand for, or make it harder for people to
buy our products. The unavailability or inadequacy of third party reimbursement
for our products would reduce or possibly eliminate demand for our products. We
are unable to predict whether governmental authorities will enact additional
legislation or regulation which will affect third party coverage and
reimbursement that reduces demand for our products.

   Continued consolidation could cause a decline in our sales. In both the U.S.
and the U.K., a small number of large wholesale distributors control a
significant share of each market. In addition, the number of independent drug
stores and small chains has decreased as retail pharmacy consolidation has
occurred. Consolidation or financial difficulties could cause customers to
reduce their inventory levels, or otherwise reduce purchases of our products.

   Any loss of our key personnel could prevent us from developing new
products. Our success is dependent on our ability to attract and retain highly
qualified management and scientific personnel. We face intense competition for
personnel from other companies, academic institutions, government entities and
other organizations. We may not be able to successfully attract and retain such
personnel. In general, we have agreements with some of our key scientific and
management personnel for periods of one year or less. The loss of such
personnel, or the inability to attract and retain the additional, highly
skilled employees required for our activities, could prevent us from developing
new products. We have key man insurance for Rolf Stahel, Chief Executive of
Shire, in the amount of $1 million.

   Our future financial results may be impacted by a number of factors, some of
which are beyond our control. Shire has experienced losses on ordinary
activities after taxation in four out of the past five fiscal years. Roberts
has experienced losses in three out of the past five fiscal years. We may not
be able to achieve sustained profitability. Our results of operations have
varied, and will vary in the future, from period to period, due to a variety of
factors, including:

  .  costs incurred to acquire, license, develop and market pharmaceuticals;

  .  changes in prescription writing practices;

  .  spending on research and development;

  .  the introduction of new products by us or our competitors;

  .  cost increases from third-party manufacturers;

  .  supply interruptions;

  .  the expiration of intellectual property protection;

  .  the availability and cost of raw materials;

  .  the mix of products sold by us;

  .  changes in marketing and sales expenditures;

                                       35
<PAGE>

  .  changes in reimbursement practices;

  .  market acceptance of our products;

  .  competitive pricing pressures; and

  .  general economic and industry conditions that affect demand for our
     products.

   A reduction in the value of the U.S. dollar could reduce our
earnings. Changes in exchange rates, particularly those between the U.S. dollar
and pound sterling will affect our results of operations. For the year ended
December 31, 1998, approximately 66% of Shire's revenue was earned in U.S.
dollars while approximately 52% of Shire's expenses were in pounds sterling.
Any material decrease in the value of the U.S. dollar compared to the pound
could reduce our earnings by decreasing the value of our revenues relative to
our expenses.

   If we are unable to renew or extend contracts with manufacturers or
licensees as they expire, we may not be able to develop or manufacture some of
our products. We have entered into licensing and co-development agreements with
a number of parties. We face the risk that, upon expiration or termination of a
third party agreement, we may not be able to renew or extend the agreement with
the third party as our interests may no longer coincide. In addition, we may
not be able to obtain an alternative supplier for the necessary goods or
services on commercially viable terms if at all. Our development agreements
generally are terminable upon the occurrence of events described in the
agreements, such as the non-payment of royalties or the insolvency of one of
the parties to the agreement, and, in some cases, upon notice. In such
circumstances we may be unable to continue to develop or market our products as
planned and could be required to abandon or divest a product line.

   The principal components of our products are active and inactive
pharmaceutical ingredients and special packaging materials. Many of these
components are available only from one supplier. We may not be able to
establish or maintain good relationships with suppliers. Additionally, we do
not know if suppliers will continue to exist or be able to supply ingredients
which meet regulatory requirements. We currently contract for some of our
manufacturing needs with manufacturers that comply with current Good
Manufacturing Practices, and other applicable laws and regulations. Our third-
party manufacturers may not be able to supply finished products which meet
these requirements. The availability of finished products may also be
interrupted because of noncompliance with regulatory requirements. In the case
of a new product, we are also subject to the risk that third party
manufacturers will not be able to meet our need to supply market requirements
for production in sufficient quantities.

   The development and approval of our products depends on our ability to
procure active ingredients and special packaging materials from sources
approved by regulatory authorities. Because the marketing approval process
requires manufacturers to specify their own proposed suppliers of active
ingredients and special packaging materials in their applications, regulatory
approval of a new supplier would be required if active ingredients or such
packaging materials were no longer available from the specified supplier. The
need to qualify a new supplier could delay our development and marketing
efforts.

   If our products are not adequately protected by our intellectual property,
competitors may manufacture and market products similar to ours. An important
part of our business strategy is the protection of our products and
technologies by means of patents, proprietary technology and trademarks. Our
success depends upon the ability of our collaborators and licensors to protect
their own intellectual property rights. Patents and patent applications
covering a number of the technologies and processes owned or licensed to us
have been granted or are pending in various countries, including the U.S. We
intend to enforce vigorously our patent rights and believe that our
collaborators intend to enforce vigorously patent rights they have licensed to
us. However, such patent rights may not prevent other entities from developing,
using or commercializing products that are similar or functionally equivalent
to our products or technologies or processes for formulating or manufacturing
similar or functionally equivalent products. Such patent rights may be
successfully challenged in the future. Additionally, our products or the
technologies or processes used to formulate or manufacture those

                                       36
<PAGE>

products may now or in the future infringe the patent rights of third parties.
It is also possible that third parties will obtain patent or other proprietary
rights that might be necessary or useful for the development, manufacture or
sale of our products. If third parties are the first to invent a particular
product or technology, it is possible that those parties will obtain patent
rights that will be sufficiently broad to prevent us or our strategic
collaborators from developing, manufacturing or selling our products. We may
need to obtain licenses for intellectual property rights from others to
develop, manufacture and market commercially viable products. We may not be
able to obtain these licenses on commercially reasonable terms, if at all. In
addition, any licensed patents or proprietary rights may not be valid and
enforceable.

   There has been substantial litigation in the pharmaceutical industry with
respect to the manufacture, use and sale of new products that are the subject
of conflicting patent rights. These lawsuits relate to the validity and
infringement of patents. The expense of defending lawsuits brought against us
could cause us not to defend these suits and abandon the products. In the past,
innovators of products which we are in the process of developing have filed
patent infringement lawsuits challenging notices of non-infringement submitted
as part of regulatory filings. These lawsuits may be brought by innovators
against us or our collaborative partners while we or our collaborative partners
pursue regulatory approvals for our products. The ultimate outcome of this type
of litigation, if brought, may not be favorable. Our own patents may be subject
to infringement by others. While we may pursue litigation in order to protect
these rights, we may not be successful in these lawsuits. We are also required
to certify to regulatory authorities, such as the FDA, when seeking approval of
some of our products that the product does not infringe upon third party
rights. A patent holder may challenge a notice of non-infringement or
invalidity by filing suit for patent infringement within 45 days of receiving
notice. This challenge, if made, would prevent regulatory approval in the U.S.
until the suit is resolved or until at least 30 months had elapsed.

   We also rely on trade secrets and other un-patented proprietary information,
which we generally seek to protect by confidentiality and nondisclosure
agreements with our employees, consultants, advisors and collaborators. These
agreements may not effectively prevent disclosure of confidential information
and may not provide us with an adequate remedy in the event of unauthorized
disclosure of such information. For example, although we rely on proprietary
information and trade secrets relating to Adderall(R), Adderall(R) is not
patent protected and competitors may be able to produce competing products. If
our employees, scientific consultants or collaborators develop inventions or
processes that may be applicable to our products under development, such
inventions and processes will not necessarily become our property, but may
remain the property of those persons or their employers. Protracted and costly
litigation could be necessary to enforce and determine the scope of our
proprietary rights. Our failure to obtain or maintain patent and trade secret
protection, for any reason, could allow other companies to make competing
products and reduce the sales of our products.

   We have filed applications to register various trademarks for use in
connection with pharmaceuticals and related laboratory services in the U.S. and
intend to continue to trademark new product names as they are developed. In
addition, with respect to certain products, we rely on the trademarks of third
parties. These trademarks may not afford adequate protection, or that we or
those third parties will have the financial resources to enforce any rights
under any of these trademarks. Our inability or the inability of these third
parties to protect their trademarks because of successful third party claims to
those trademarks could allow others to use our trademarks and dilute their
value.

   If we do not achieve a diversified customer base, we will be vulnerable to
the loss of important individual customers. In the U.S., our customers include
McKesson Corp., Bergen Brunswig Corp. and Cardinal Health, Inc. In the U.K.,
our customers include The Boots Company plc, AAH Pharmaceuticals Limited and
Unichem plc. For the fiscal year ended December 31 1998, Shire's two largest
customers, McKesson Corp. and Cardinal Health, Inc. accounted for approximately
20% and 9% of its revenues, respectively. The loss of either of these customer
accounts could substantially reduce our revenues.


                                       37
<PAGE>

The following are risks that relate to Shire and will relate to the combined
company after the merger.

   Any decrease in the sale of Adderall(R) could significantly reduce
revenues. In 1998, sales of Adderall(R) were approximately $80.5 million,
representing approximately 59% of Shire's revenues. Any factors adversely
affecting the sale or production of Adderall(R) would significantly reduce
Shire's revenues. An explosion in August 1998 at Shire's then supplier of the
active ingredients for Adderall(R) halted its production for a total of 84
days. If a similar incident were to occur again, we would experience a
substantial decrease in revenues.

   Other factors which could adversely affect sales of Adderall(R) include:

  .  development of competitive pharmaceuticals;

  .  technological advances;

  .  increased production costs;

  .  marketing or pricing actions by Shire's competitors;

  .  changes in prescription writing practices;

  .  the occurrence of adverse reactions to Adderall;

  .  changes in reimbursement policies of third party payors; or

  .  product liability claims.

   Shire is named as a defendant in a large number of lawsuits involving
phentermine and may incur significant liability if it loses one or more of
these suits. Shire is currently a defendant in approximately 3,000 lawsuits, in
both federal and state courts, which seek damages for, among other things,
personal injury arising from our phentermine products supplied for the
treatment of obesity by Shire and several other pharmaceutical companies. Shire
has been sued as a manufacturer and distributor of phentermine, an anorectic
used in the short-term treatment of obesity and one of the products addressed
by the lawsuits. If Shire is found liable in some or all of these lawsuits for
damages in excess of its assets, it would be required to consider reorganizing
and seeking protection in bankruptcy or initiating insolvency proceedings. The
suits relate to phentermine either alone or together with fenfluramine or
dexfenfluramine. In 87 of these suits, the plaintiffs have specifically alleged
that they used Oby-Cap or Oby-Trim, phentermine products produced by Shire. The
lawsuits generally allege the following claims:

  .  the defendants marketed phentermine and the other products for the
     treatment of obesity and misled users about the products and the dangers
     associated with them;

  .  the defendants failed to adequately test phentermine individually and
     when taken in combination with the other drugs; and

  .  the defendants knew or should have known about the negative effects of
     the drugs and should have informed the public about such risks and/or
     failed to provide appropriate warning labels.

   Shire became involved with phentermine through its acquisition of certain
assets of Rexar Pharmacal Corp. in January 1994. In addition to liability as a
result of its own production of Oby-Cap, plaintiffs may seek to impose
liability on Shire as a successor to Rexar. Class certification has been sought
for certain of the claims made against Shire and the other defendants. In
addition, pending federal lawsuits have been consolidated as a multidistrict
litigation in the Eastern District of Pennsylvania. Shire intends to vigorously
defend all the lawsuits and pursue all available reasonable defenses. Legal
expenses have thus far been paid by the insurers of Eon Labs Manufacturing
Inc., the supplier to Shire. Through approximately August 1999, Eon and its
distributors, including Shire, had exhausted $25 million in insurance proceeds
defending the lawsuits. Additional insurance is available to Shire and the
other Eon distributors through Eon's carriers in the amount of $22.75 million
in the aggregate. In addition, Shire has its own insurance up to a maximum of
$3 million for lawsuits filed in the period to April 28, 1998, an unlimited
indemnity given by Eon and a limited indemnity from the former shareholders of
SRI given at the time of acquisition of SRI by Shire. Shire has already spent a
substantial amount of resources in managing these lawsuits and will continue to
do so.


                                       38
<PAGE>

   We will have to make substantial severance payments to Roberts' senior
management team if they leave Shire or are terminated without cause. Fifteen
senior executives of Roberts, comprising all the Senior Vice Presidents and
Vice Presidents, are entitled under their agreements with Roberts to be paid
cash if they terminate their employment after one year and before two years
following completion of the merger or if they are terminated by Shire without
cause at any time. The total amount of payments that could be made by Shire is
$7.0 million. In addition, as a result of accelerated vesting following the
merger, the same executives can exercise a total of 936,550 options.

                                       39
<PAGE>

                      WHERE YOU CAN FIND MORE INFORMATION

   Roberts and Shire are each subject to the informational requirements of the
Securities Exchange Act of 1934, and Roberts files reports, proxy statements
and other information, and Shire files annual reports and certain other
information, with the Securities and Exchange Commission, or the SEC. You can
inspect and copy those reports, proxy statements and other information at the
SEC's public reference room located at Judiciary Plaza, 450 Fifth Street, N.W.,
Room 1024, Washington, D.C. 20549, and at the public reference facilities in
the SEC's regional offices located at: 7 World Trade Center, 13th Floor, New
York, New York 10048, and at Citicorp Center, 500 West Madison Street, Suite
1400, Chicago, Illinois 60661. You can obtain copies of this material at
prescribed rates by writing to the Securities and Exchange Commission, Public
Reference Section, 450 Fifth Street, N.W., Washington, D.C. 20549. Information
on the operation of the Public Reference Room may be obtained by calling the
SEC toll free at 1-800-SEC-0330. The SEC also maintains an internet Website
that contains reports, proxy and information statements and other information
regarding registrants that file electronically with the SEC, including Roberts
but not Shire. The address of this Website is http://www.sec.gov.

   Shire has filed with the SEC a registration statement on Form F-4 to
register the Shire ordinary shares, including ordinary shares underlying the
ADSs, to be issued to Roberts shareholders in the merger and a registration
statement on Form F-6 in respect of the Shire ADSs under the Securities Act.
This Prospectus-Proxy Statement is a part of the registration statement on Form
F-4 and constitutes a prospectus of Shire in respect of the Shire ordinary
shares underlying the Shire ADSs and the Shire ordinary shares to be issued to
Roberts shareholders in connection with the merger, in addition to being a
proxy statement of Roberts for the special meeting. As allowed by SEC rules,
this Prospectus-Proxy Statement does not contain all the information you can
find in the registration statements or the exhibits to the registration
statements. Statements contained in this Prospectus-Proxy Statement concerning
any other documents are not necessarily complete and, in each instance,
reference is made to the copies of these documents filed as exhibits to the
registration statements. Each of these statements is qualified in its entirety
by this reference.

                                       40
<PAGE>

                         CURRENCIES AND EXCHANGE RATES

   References in this Prospectus-Proxy Statement to "dollars," "$" or "c" are
to the currency of the U.S., and references to "pounds sterling," "pounds,"
"(Pounds)," "pence" or "p" are to the currency of the United Kingdom. There are
100 pence to each pound. Solely for your convenience, this Prospectus-Proxy
Statement contains translations of certain pounds sterling amounts into U.S.
dollars at specified rates. These translations should not be taken as
assurances that the pounds sterling amounts currently represent these U.S.
dollar amounts or could be converted into U.S. dollars at the rate indicated or
at any other rate at any time.

   In this Prospectus-Proxy Statement, unless otherwise stated, pounds sterling
have been translated into U.S. dollars at a rate of $1.64 per (Pounds)1.00, the
noon buying rate in New York City for cable transfers in pounds sterling as
certified for customs purposes by the Federal Reserve Bank of New York on
September 30, 1999, which we refer to in this Prospectus-Proxy Statement as the
noon buying rate. On     , 1999, the noon buying rate was $     per
(Pounds)1.00.

   The following table sets forth, for each period indicated, the high and low
noon buying rates for one pound sterling expressed in U.S. dollars, the average
noon buying rate during the period, and the noon buying rate at the end of the
period, based upon information provided by the Federal Reserve Bank of New
York:

<TABLE>
<CAPTION>
                                            Nine Months
                                               Ended     Year Ended December 31,
                                           September 30, -----------------------
                                               1999       1998    1997    1996
                                           ------------- ------- ------- -------
<S>                                        <C>           <C>     <C>     <C>
High......................................    $1.6585    $1.7222 $1.7035 $1.7123
Low.......................................    $1.5515    $1.6114 $1.5775 $1.4948
Average...................................    $1.6131    $1.6573 $1.6376 $1.5607
Period End................................    $1.6457    $1.6628 $1.6427 $1.7123
</TABLE>

   The following table sets forth, for each period indicated, the high and low
rates for one U.S. dollar expressed in pounds sterling, the average rate during
the period, and the rate at the end of this period, based upon information
obtained from the Federal Reserve Bank of New York:

<TABLE>
<CAPTION>
                     Nine Months
                        Ended                Year Ended December 31,
                    September 30,  --------------------------------------------
                         1999           1998           1997           1996
                    -------------- -------------- -------------- --------------
<S>                 <C>            <C>            <C>            <C>
High............... (Pounds)0.6030 (Pounds)0.5807 (Pounds)0.5870 (Pounds)0.5840
Low................ (Pounds)0.6445 (Pounds)0.6206 (Pounds)0.6339 (Pounds)0.6690
Average............ (Pounds)0.6199 (Pounds)0.6034 (Pounds)0.6106 (Pounds)0.6408
Period End......... (Pounds)0.6076 (Pounds)0.6014 (Pounds)0.6088 (Pounds)0.5840
</TABLE>

                                       41
<PAGE>

                             SHIRE AFTER THE MERGER

Overview

   After the merger, we will be a specialty pharmaceutical company with four
areas of therapeutic focus: central nervous system disorders, gastrointestinal
disorders, metabolic/bone diseases and cancer. We refer to ourselves as
"specialty" because our principal products tend to be prescribed by specialists
as opposed to primary care physicians. In the U.S., the number of prescribers
specializing in a particular disease area tends to range from 2,000 to 10,000
compared with a total of approximately 200,000 primary care physicians.
Accordingly, a comparatively small salesforce such as ours can promote
specialty products effectively but could not be expected to achieve the
necessary coverage of primary care physicians.

   Our principal products will include Adderall(R) for the treatment of
Attention Deficit Hyperactivity Disorder, Carbatrol(R) for the treatment of
epilepsy, Pentasa(R) for the treatment of ulcerative colitis, Agrylin(R) for
the treatment of elevated blood platelets and ProAmatine(R) for the treatment
of low blood pressure in the U.S. and the Calcichew(R) range used primarily as
adjuncts in the treatment of osteoporosis in the U.K. In addition, we will have
a number of products in late stage development including Reminyl(R) for the
treatment of Alzheimer's disease, Dirame(R) for the treatment of moderate to
moderately severe pain, Lambda(R) for the treatment of high blood phosphate
levels associated with kidney failure, RL0903 for the treatment of prostate
cancer and Emitasol(R) for the treatment of nausea and vomiting.

   Roberts has license agreements with other pharmaceutical companies giving
Roberts exclusive rights to develop and market its three largest products,
Pentasa(R), ProAmatine(R) and Agrylin(R), and some of its products under
development, including RL0903, Dirame(R), Tazofelone(R) and Sampatrilat(R).
Roberts' exclusive rights under these agreements will not change as a result of
the merger. In addition, ProAmatine(R) and Agrylin(R), which have been granted
Orphan Drug status by the FDA, will continue to have Orphan Drug status after
the merger.

   After the merger, our revenues will continue to be derived from three
sources: sales of products by our own sales and marketing operations
principally in the U.S., the U.K. and Canada; licensing and development fees;
and royalties. On a pro forma basis, we had revenues (turnover) of
(Pounds)186.0 million and a profit after tax of (Pounds)14.1 million for the
year ended December 31, 1998 or $308.8 million and $23.5 million, respectively,
in each case based upon an exchange rate of $1.66 for each pound sterling, the
average of the noon buying rates for the period.

Strategy and Approach

   Our strategy is to develop products and, where appropriate, to market them
through our own sales organizations in the major markets of the world. The key
elements of our operating strategy are described below:

   Market proprietary products through our own sales force. We believe that
higher financial returns can be achieved by marketing our products directly, as
opposed to receiving royalties on licensees' sales. The merger significantly
enhances our sales and marketing capability in the U.S. and the U.K. The merger
also provides a platform for expansion in Canada through Roberts' operation
there. We intend to continue to expand our sales and marketing capability, as
opportunities arise, particularly in the major European markets. If suitable
opportunities cannot be found, we intend to establish our own sales and
marketing organizations in those territories, possibly in conjunction with the
purchase of a product or products from third parties.

   Manage development risk. Recognizing the inherent risks of failure in drug
development, both Roberts and Shire have historically sought to manage
development risk by maintaining a broad and balanced development portfolio.
Shire has also sought to selectively leverage relationships with collaborative
parties. Neither company has undertaken discovery research for new chemical
entities. Instead, as a combined company we anticipate continuing to rely on
our broad network of contacts to identify product candidates which can be
developed either internally or through collaborative partnerships.

                                       42
<PAGE>

   Focus on late-stage development products. Roberts has organized its
activities to focus on late-stage development drugs. Shire has also sought to
identify promising product candidates already under development or exploit a
number of proprietary drug delivery technologies to develop products. In
addition to developing our proprietary pipeline products, our principal
objective will be to concentrate our operations on licensing, acquiring,
developing, marketing and selling proven products and technologies. Both
companies have

Sales and Marketing

   We intend to use our sales and marketing infrastructure to sell and market
most of our licensed and internally developed products. Our combined sales and
marketing operations in the U.S., the U.K. and Canada will consist of 269, 92
and 25 sales representatives, respectively. Following the merger, this expanded
sales force will have a broader portfolio of products with opportunities to
benefit from increased coverage. We also believe that the merger will create a
larger base from which to build a sales and marketing infrastructure in
Continental Europe.

   On October 25, 1999, Shire announced that it had acquired the German and
French subsidiaries of Fuisz Technologies Limited and entered into an agreement
to acquire Fuisz's Italian subsidiary. The purchase price for the three
subsidiaries, all of which are marketing companies, was $39.5 million. All
three companies have a low asset base and no manufacturing facilities and
consist of a total sales force of 55, of which 20 are employees and the
remainder are contract sales representatives.

Combined Marketed Products

   The table below lists the key currently marketed products of Shire and
Roberts by therapeutic areas, indicating the owner or licensor of the product
and who is marketing the product in which territory.

<TABLE>
<CAPTION>
                                                          Marketed By/Relevant
Products         Principal Indication(s)  Owner/Licensor        Territory
- --------         -----------------------  --------------  --------------------
<S>              <C>                      <C>            <C>
Treatments for central nervous system
 disorders
Adderall(R)      ADHD                     Shire          Shire/U.S.
DextroStat(R)    ADHD                     Shire          Shire/U.S.
Carbatrol(R)     Epilepsy                 Shire          Shire/U.S.
Treatments for metabolic/bone diseases
Calcichew(R)
 range           Osteoporosis adjunct     Nycomed        Shire/U.K. and Ireland
Treatments for blood disorders/cancer
Agrylin(R)       Elevated blood platelets Roberts        Roberts/U.S. and Canada
ProAmatine(R)    Low blood pressure       Nycomed        Roberts/U.S. and Canada
Treatments for gastrointestinal
 disorders
Pentasa(R)       Ulcerative colitis       Ferring        Roberts/U.S.
Treatments for other indications
Noroxin(R)       Urinary tract infections Merck          Roberts/U.S.
Colace(R)/Peri-
 Colace(R)       Constipation             Roberts        Roberts/U.S. and Canada
</TABLE>

Products Under Development

   After the merger, we will seek to maintain a broad and balanced approach to
our development of new products by, among other things, leveraging third-party
research and development expertise. We have no plans to become directly
involved in discovery research for new chemical entities, preferring instead to
license

                                       43
<PAGE>

compounds from third parties and develop them through the clinical phase with a
view to marketing them through our own sales and marketing organization. On a
combined basis Roberts and Shire spent approximately $60 million on research
and development in the year ended December 31, 1998.

   The table below lists the key products under development by Shire and
Roberts by therapeutic area, including their development status and their
territorial rights. Where either company has secured a licensee for a product,
this fact is also indicated.

<TABLE>
<CAPTION>
                    Principal
 Product(s)         Indication(s)         Status          Territorial Rights    Licensee(s)
 ----------         ------------          ------          ------------------    ----------
 <C>                <S>                   <C>             <C>                   <C>
 Treatments for central nervous system disorders
 Reminyl(R)
 (galantamine)      Alzheimer's disease   In registration Global                 Janssen
 Dirame(R)          Moderate/moderately   Phase III       Global
                    severe pain
 SLI381             ADHD                  Phase I         Global
 SPD417             Manic depression      Phase I         Global
 SPD503             ADHD                  Pre-clinical    Global
 SPD418             Epilepsy              Pre-clinical    Global
 SPC502             Stroke                Pre-clinical    Global excl. Nordic
                                                          and Baltic countries
 Treatments for metabolic/bone diseases
 Lambda(R)          High blood            Phase III       Global
                    phosphate
                    levels in patients
                    with
                    kidney failure
 ProAmatine(R)      Low blood pressure    Phase II        U.S., U.K., Canada
                    in
                    dialysis patients
 Treatments for gastroenterological disorders
 Pentasa(R) (500mg) Ulcerative colitis    Phase III       U.S.
 Emitasol(R)        Nausea and vomiting   Phase III       U.S., Canada
                    Inflammatory bowel
 Tazofelone(R)      disease               Phase II        Global
                    Irritable bowel
 LY315535           syndrome              Phase I         North America
 Treatments for oncological diseases
 RL0903             Prostate cancer       Phase III       North America, Europe
</TABLE>

Drug Delivery Technologies

   We have a platform of five drug delivery technologies that can be applied to
drugs in order to enhance their effectiveness or their convenience to patients
in terms of dosage regimen. Generally, this involves re-formulating the drug
into a new delivery system designed either to enhance the absorption of the
drug into the blood stream or, alternatively, to delay absorption of the drug
into the bloodstream, thereby requiring the patient to take fewer daily doses.

   Our portfolio of drug delivery technologies includes three technologies
designed to improve the oral delivery of drugs, a technology for rapid
absorption through the tissues of the mouth and a system for delivering drug
through the skin from an adhesive patch. We intend to make these technologies
available to third parties in return for development fees, milestones and
royalties. We also intend to employ these technologies selectively to products
being developed internally where we believe the characteristics of the product
can be improved or modified to secure a competitive advantage.

                                       44
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                              THE SPECIAL MEETING

Date, Time, Place and Purpose

   This Prospectus-Proxy Statement is being furnished to Roberts shareholders
in connection with the solicitation of proxies by the Roberts board for use at
the special meeting scheduled to be held at Roberts' offices at Meridian
Center II, 4 Industrial Way West, Eatontown, New Jersey 07724, on     , 1999,
at 10:00 a.m., local time, and at any adjournment or postponement thereof.

Matters to Be Considered at the Special Meeting

   At the special meeting, Roberts shareholders will be asked to consider and
vote on the merger proposal.

Record Date; Voting Rights; Voting at the Meeting

   The Roberts board has fixed October 27, 1999 as the record date for
determination of Roberts shareholders entitled to notice of, and to vote at,
the special meeting. Each holder of record of Roberts shares on the record
date is entitled to cast one vote per share, exercisable in person or by a
properly executed proxy, on each matter submitted at the special meeting. On
the record date, there were 32,046,720 Roberts shares outstanding and entitled
to vote which were held by approximately 920 holders of record.

   The presence, in person or by a properly executed proxy, of a majority of
the Roberts shares outstanding and entitled to vote at the special meeting is
necessary to constitute a quorum at the special meeting. The merger proposal
requires the affirmative vote of at least two-thirds of the votes cast by the
holders of Roberts shares present or represented by proxy at the special
meeting. Directors and officers of Roberts and their affiliates collectively
own shares representing approximately 5.8% of the outstanding Roberts common
stock. Dr. Robert A. Vukovich, Chairman of the Board of Roberts and holder of
5.4% of the outstanding Roberts common stock has agreed to vote his shares in
favor of the merger. Yamanouchi Group Holdings Inc., which owns 15.8% of
Roberts' common stock, has also agreed to vote its shares in favor of the
merger.

Voting of Proxies

   All Roberts shareholders who are entitled to vote and are represented at
the special meeting by properly executed proxies received prior to or at the
special meeting and not revoked will be voted at the special meeting in
accordance with the instructions indicated in the proxies. If no instructions
are indicated, those proxies will be voted FOR approval of the merger
proposal. Under rules applicable to brokers, a broker is precluded from
exercising voting discretion with respect to the approval of the merger
proposal and thus, absent specific instructions from the beneficial owner of
those Roberts shares, is not empowered to vote those Roberts shares for or
against the merger proposal. Roberts shares represented by those "broker non-
votes" as well as Roberts shares held by shareholders who abstain from voting
on the merger proposal will be counted for purposes of determining whether
there is a quorum at the special meeting. However, neither abstentions nor
broker "non-votes" are considered votes for or against the merger and will
therefore have no impact on the approval of the merger.

   Any proxy given pursuant to this solicitation may be revoked by the person
giving it at any time before it is voted. Proxies may be revoked by:

  . filing (including by telegram or facsimile) with the Secretary of
    Roberts, before the taking of the vote at the special meeting, a written
    notice of revocation bearing a later date than the date of the proxy or
    by giving notice of revocation in the open meeting;

  .submitting a later-dated proxy; or

  .attending the special meeting and voting in person.

                                      45
<PAGE>

   In order to vote in person at the special meeting, Roberts shareholders must
attend the meeting and cast their votes in accordance with the voting
procedures established for such meeting. Attendance at the special meeting will
not in and of itself constitute a revocation of a proxy. Any written notice of
revocation or subsequent proxy must be sent to: Roberts Pharmaceutical
Corporation, Meridian Center II, 4 Industrial Way West, Eatontown, New Jersey
07724, Attention: Secretary.

   Roberts will bear the costs of the special meeting and the solicitation of
proxies.

                                       46
<PAGE>

                                   THE MERGER

Background of the Merger

   The Roberts board and management regularly consider Roberts' strategic
alternatives as part of their ongoing efforts to enhance shareholder value.
These alternatives have included merging with a strategic partner to gain
access to greater financial resources and marketing capabilities.

   Over the past several years, directors and management of Roberts have had
contact with a number of organizations that were potentially interested in a
strategic combination. In May 1998, Roberts engaged PaineWebber Incorporated to
provide financial advice in connection with possible strategic combinations. In
addition to its discussions with Shire, from June 1998 to May 1999, Roberts and
PaineWebber also had exploratory discussions from time to time with, and in
certain cases furnished confidential information to, five large, fully
integrated pharmaceutical companies. However, these discussions were
exploratory and did not progress to the point of a comprehensive exchange of
information or full negotiations of a price or structure for a transaction that
the Roberts board believed worthy of consideration.

   Following discussions between Shire and Bear, Stearns & Co. Inc. and its
affiliate Bear Stearns International Limited on various strategic combination
alternatives in the specialty pharmaceutical sector, Bear Stearns arranged an
introductory meeting between Rolf Stahel, Chief Executive of Shire, and John T.
Spitznagel, President and Chief Executive Officer of Roberts, on May 17, 1999.

   Shire and Roberts executed reciprocal confidentiality agreements on June 1,
1999, prior to a full day meeting at the offices of Bear Stearns in New York
City during which Shire presented Roberts with an overview of its business,
Roberts presented Shire with an overview of its business and preliminary
discussions regarding a potential combination were held. Additional meetings
between the representatives of Shire and Roberts were held the following day at
Roberts' Eatontown, New Jersey headquarters and Roberts' Oakville, Ontario,
Canada facility. On June 16, 1999, Shire delivered a letter to Roberts setting
forth a non-binding indication of interest at $25-26 of Shire shares for the
outstanding shares of Roberts. This price range represented a 36 to 41% premium
over Roberts' June 15, 1999 stock price and a 32 to 37% premium over the
average closing price for the 20 previous trading days.

   At a telephonic meeting held on June 21, 1999, the Roberts board considered
Roberts' strategic alternatives in light of the terms of Shire's initial
proposal and exploratory discussions with other potential merger partners.
Subsequent to such meeting, Roberts indicated to Shire that the $25-26
consideration outlined in Shire's initial proposal was insufficient. In order
to evaluate the possibility of increasing its bid, Shire requested the ability
to pursue additional due diligence, including further investigation of Roberts'
existing and pipeline drugs and potential combination synergies.

   Following agreement by Roberts to allow additional due diligence, meetings
between the senior management of Roberts and Shire and their advisors took
place in New York City on June 28 and 29, 1999 at the offices of PaineWebber.
During these meetings Roberts made available detailed business, product,
financial and legal information, among other items. In addition, senior
management of both Shire and Roberts discussed their respective operations and
the expected benefits of a merger of the two companies. On June 29, 1999, the
Roberts board held a telephonic meeting to discuss the progress of due
diligence. At this meeting, Roberts' financial advisors discussed generally the
mergers and acquisitions activity in the pharmaceutical and biotechnology
industry. The Roberts board then authorized management to continue its
discussions with Shire.

   After this meeting a non-binding proposal dated July 1, 1999 was sent by
Shire to Roberts in which Shire proposed a fixed exchange ratio of 1.1374 ADSs
for each share of Roberts common stock, which implied an offer price of $30.00
based on the closing price of Shire ADSs on July 1, 1999. The implied offer of
$30.00 represented a 25% premium over the Roberts June 30, 1999 stock price and
a 56% premium over the average closing price for the 20 previous trading days.

                                       47
<PAGE>

   At a telephonic meeting held on July 2, 1999, the Roberts board considered
Shire's revised proposal and directed management and its advisors to proceed
with additional due diligence. At the meeting, Roberts' financial advisors
reviewed with the Roberts board certain information concerning Shire and the
proposed terms of a merger.

   Further due diligence meetings were held on July 8, 1999 and July 9, 1999 at
Shire's corporate offices in Andover, U.K. Concurrently with such due diligence
meetings, meetings were held at Shire Laboratories in Rockville, Maryland on
July 8, 1999 and at Shire Richwood in Florence, Kentucky on July 9, 1999. On
July 12, 1999, the Roberts board held a telephonic meeting to discuss the
proposed transaction with Shire. Also participating in the meeting were
Roberts' financial and legal advisors. After a review of the due diligence
conducted by Roberts management and by PaineWebber, the Roberts board
authorized management to proceed with negotiation of definitive agreements for
the proposed business combination.

   From July 14 through July 16, 1999, Roberts' U.S. special counsel conducted
legal due diligence at the offices of Shire's U.S. legal counsel. On July 19,
1999, Roberts' counsel in the U.K. conducted legal due diligence at the offices
of Shire in Andover, U.K. Between July 12 and July 21, Shire conducted
additional due diligence with respect to Roberts. During the period from July 9
to July 21, the transaction documents, including the merger agreement, option
agreement, shareholder agreements and John T. Spitznagel's consulting
agreement, were negotiated among the respective parties, including Shire,
Roberts and their respective legal, tax and financial advisors. Discussions
included the exchange ratio, the conditions under which the termination fees
would be paid, the terms and conditions of the option agreement, and the terms
and conditions of John T. Spitznagel's ongoing consulting agreement.

   On July 19, 1999, the Roberts board held a telephonic board meeting with its
advisors in attendance at which Roberts management reported on the status of
the ongoing discussions with Shire. Based on this report, the Roberts board
authorized management to continue negotiations to finalize the proposed
business combination transaction with Shire's management and its advisors.

   On July 22, 1999, the Roberts board met to discuss the merger, the terms of
the merger agreement, including the proposed exchange ratio, the option
agreement and the shareholder agreements. Representatives of PaineWebber and
Roberts' legal counsel attended the meeting. At the meeting, the Roberts board
reviewed various materials relevant to the transaction and received
presentations from Roberts management, its legal counsel, its financial
advisor, PaineWebber, and its independent auditors. Included in the
presentation was a review of the principal terms of the transaction, including
related tax and accounting treatment, the regulatory approvals required to
consummate the proposed merger and the fiduciary responsibilities of the
Roberts board in considering the proposed transaction. The Roberts board also
gave specific consideration to the option agreement and the termination fee of
$30 million payable to Shire in certain circumstances pursuant to the merger
agreement. The Roberts board noted that an option agreement and a fee of this
kind were both reasonable and customary in the market, and were each demanded
by Shire as a condition to executing the merger agreement. The Roberts board
also determined that the terms of the option agreement and termination fee
which were negotiated by management were sufficiently limited so as not to
interfere with a bid from any source the board believed could make a competing
offer. In addition, PaineWebber delivered its opinion to the Roberts board that
the proposed merger consideration is fair, from a financial point of view, to
the holders of Roberts shares. The PaineWebber opinion is attached to this
Prospectus-Proxy Statement as Annex B. The Roberts board then unanimously
approved the merger agreement and option agreement.

   Also on July 22, 1999, the Shire board met to discuss the merger, the terms
of the merger agreement and the proposed exchange ratio. Representatives of
Bear Stearns and Shire's legal counsel attended the meeting. At the meeting,
the opinion of Bear, Stearns & Co. Inc. was delivered to the Shire board that
the exchange ratio is fair, from a financial point of view, to Shire. The Bear
Stearns opinion is attached to this Prospectus-Proxy Statement as Annex C. The
Shire board also considered other key terms of the merger agreement, the option
agreement, the shareholder agreements and John T. Spitznagel's consulting
agreement.

                                       48
<PAGE>

The Shire board also gave specific consideration to the Roberts termination fee
of $30 million contained in the merger agreement. The Shire board noted that
such a fee is both reasonable and customary in the market, and was required by
Roberts as a condition to executing the merger agreement. The Shire board then
approved the merger agreement and option agreement, contingent upon approval of
a special committee, consisting of Rolf Stahel and Stephen Stamp, pending the
resolution of certain outstanding points to the satisfaction of such committee.

   During July 22 and 23, 1999 negotiations continued between the
representatives of Shire and Roberts, and on July 23, 1999, after the close of
trading of the relevant stock markets in both the U.S. and the U.K., the merger
agreement, option agreement and shareholder agreements were executed.

Roberts' Reasons for the Merger; Recommendation of the Roberts Board of
Directors

   On July 22, 1999, the Roberts board, by a unanimous vote, concluded that the
merger, the terms of the merger agreement, the option agreement and the
transactions contemplated thereby were in the best interests of Roberts and its
shareholders. Accordingly, the Roberts board adopted the merger agreement and
recommended that the shareholders of Roberts approve the merger agreement. In
determining whether to recommend approval of the merger agreement and the
transactions contemplated thereby and in adopting the merger agreement and the
option agreement, the Roberts board considered each of the following material
factors:

  .Consideration Offered and Premium over Roberts' Share Price. The value of
    the ADS consideration and the ordinary share consideration provided for
    in the merger agreement relative to the then-current market price of
    Roberts shares. Based on the market prices of the ADSs and Roberts shares
    on July 21, 1999, Roberts shareholders would receive a premium of
    approximately 25% over the closing sale price of Roberts shares of
    $24.50. The premium is approximately 35% over the average closing sale
    price of Roberts shares for the period of twenty consecutive trading days
    ending on July 21, 1999.

  .Fairness Opinion. The opinion of PaineWebber delivered to the Roberts
    board that, as of the date of the opinion, the merger consideration under
    the merger agreement was fair, from a financial point of view, to holders
    of Roberts shares.

  .Substantial Ownership of Roberts Shareholders in Combined Company. That
    holders of Roberts shares will receive approximately 42% to approximately
    47% of the total issued share capital of the combined company following
    the merger depending on the exchange ratio.

  .Large Shareholders' Support of Merger. The willingness of major holders of
    Roberts shares and of Shire ordinary shares to execute shareholder
    agreements evidencing their agreement to vote their shares to approve the
    merger agreement.

  .Broader Product Offering. The ability of the combined Roberts and Shire to
    diversify its product offerings and increase the number of products with
    strong market positions. The additional resources and sales force
    coverage that the combined company will possess are expected to enhance
    the sales potential of its key products, including Adderall, Pentasa,
    Carbatrol, Agrylin and ProAmatine.

  .Broader Development Portfolio. That key late-stage development projects of
    the combined Shire and Roberts will include Reminyl(R) (galantamine) for
    Alzheimer's disease, Dirame(R) (propiram) for analgesia, Emitasol(R)
    (nasal metoclopramide) for nausea, Lambda(R) (lanthanum carbonate) for
    hyperphosphatemia and RL0903 (LHRH implant) for prostate cancer. The
    combined company will have a broader development portfolio which will
    include one product in registration and five products in Phase III
    trials.

  .Access to Greater Financial Resources to Pursue Further Growth
    Opportunities. As of June 30, 1999 the aggregated indebtedness and the
    aggregated cash and investments of the combined company were $130 million
    and $126 million, respectively.

                                       49
<PAGE>

  .Increased Marketing Capability. The combined company will have a combined
    sales force of 269, 92 and 25 sales representatives in the U.S., the U.K.
    and Canada, respectively. The combined company should be able to expand
    its direct marketing capability into continental Europe, through a
    potential combination of product and company acquisitions. Further,
    because Roberts and Shire do not have competing products, their separate
    sales forces should compliment each other and afford new marketing
    avenues for the products offered by Roberts and Shire.

  .Increased Investor Profile and Liquidity. The combined company is expected
    to benefit from a wider shareholder base and the greater liquidity of its
    securities.

  .Transaction Is Tax-Free. The U.S. federal income tax consequences of the
    transaction, including the ability of Roberts shareholders to have a tax-
    free exchange of their Roberts shares, and the risk that the merger might
    fail to qualify as a tax-free reorganization under U.S. tax law as a
    result of actions outside the control of Roberts.

  .Pooling of Interests Accounting Treatment. The intended accounting of the
    merger as a pooling of interests under U.S. GAAP which results in
    combined financial statements prepared on a basis consistent with the
    underlying view that shareholder interests in the two companies have
    simply been combined, and in the preservation of the historical cost
    approach for both Roberts and Shire. This will facilitate future
    comparison and benchmarking of the combined company against key
    international competitors.

  .Earnings of Combined Company. That the combination of Roberts and Shire,
    without taking into account any expected synergies, is projected to be
    dilutive to U.S. GAAP earnings through 2000 and accretive to earnings
    starting 2001.

  .Strategic Alternatives for Increasing Shareholder Value. The Roberts board
    considered pursuing several alternatives to increasing shareholder value,
    including the merger with Shire, other potential business combinations,
    strategic joint ventures or partnerships and remaining an independent
    company. PaineWebber had been retained to assist Roberts in exploring
    these options. Based on all of the information available to the Roberts
    board, it determined that the strategic combination with Shire and the
    premium being offered by it presented, at that point, the best
    opportunity to create greater shareholder value.

  .No Other Formal Offers. Discussions with other parties led to no formal
    offers and the Roberts board believed there were no, and there would not
    be in the near future any, other business combination opportunities with
    the significant premium offered by Shire.

  .Interests of Certain Persons. That certain members of the Roberts board
    and management had interests in the merger different from the interests
    of the shareholders. The interests of these persons are more fully
    described under the heading "Interests in the Merger of Persons
    Affiliated with Roberts."

  .The Effect of Merger Agreement on Third Party Proposals. The Roberts board
    considered the possible effect of the terms of the merger agreement with
    respect to any third party proposals to acquire Roberts after the
    execution of the merger agreement. The Roberts board considered that the
    provisions of the merger agreement providing for the payment of a
    termination fee, as well as the provisions of the option agreement, could
    have the effect of discouraging alternative proposals for a business
    combination with Roberts. If any third party proposal were made that the
    Roberts board determined to be a superior proposal (see "The Merger
    Agreement"), the Roberts board could only terminate the merger agreement
    if it paid a termination fee to Shire.

  .Shire Product Offering and Development Pipeline. That Shire has only one
    major product, Adderall, and most of its products in development are
    still in the early stages of the development cycle. In addition, Shire's
    most significant product in development, Reminyl, has been licensed to a
    third party and represents only a revenue stream.

                                       50
<PAGE>

  .Regulatory Approval Not Certain. That the merger is subject to clearance
    under anti-trust laws in both the United States and the United Kingdom.
    The combination of Shire and Roberts requires the filing of merger
    notifications in the United States to the Federal Trade Commission and
    the Department of Justice, and in the United Kingdom to the Office of
    Fair Trading. The merger could be blocked or delayed by any of the
    Federal Trade Commission, the Department of Justice or the Office of Fair
    Trading.

  .Restrictions on Conduct of Business Pending Merger Completion. That the
    terms and conditions of the merger agreement include restrictions on the
    conduct of Roberts' business pending completion of the merger and permit
    Roberts to conduct its business only in the ordinary course during that
    period.

  .Ongoing Business Relationships. That pending completion of the merger,
    Roberts' relationships with employees, customers, government agencies and
    partners might be damaged because of the uncertainty of completing the
    transaction.

  .Independent Business. That following the merger, Roberts will no longer be
    an independent company.

  .Roberts' Shareholders Will Hold ADSs and not Common Stock. That in the
    merger the Roberts shareholders will have their holdings represented by
    Shire ADSs or Shire ordinary shares and will have a currency exchange
    risk as a result of future dividends having to be converted from pounds
    to dollars.

   In light of the Roberts board's knowledge of the business and operations of
Roberts and its business judgment, the Roberts board considered and evaluated
each of the factors listed above during the course of its deliberations before
approving the merger agreement. In view of the wide variety of factors
considered in connection with its evaluation of the merger, the Roberts board
found it impracticable to, and did not, quantify or otherwise attempt to assign
relative weights to the specific factors considered in making its
determinations.

   After considering all of the foregoing factors, the Roberts board concluded
that a combination with Shire, under the terms in the merger agreement and the
related documentation, is in the best interests of Roberts and its
shareholders. The Roberts board believes the factors listed above, when
considered together, support the fairness of the merger to Roberts and its
shareholders and the Roberts board believes that these factors, when considered
together, support its recommendation that Roberts shareholders vote for
approval of the merger agreement.

Shire's Reasons for the Merger

   Shire's management believes that the merger brings together two of the
fastest growing publicly traded specialty pharmaceutical companies, which share
a common strategic vision. Both companies have built effective sales and
marketing organizations to promote specialty products to defined customer
groups. In addition, through selective in-licensing of development compounds,
both companies seek to build long term shareholder value by taking these
compounds through the development and registration process. The principal
benefits of the merger are expected to include:

  .Broadens product portfolio and expands areas of therapeutic focus. In
    Adderall(R), Pentasa(R), Carbatrol(R), Agrylin(R) and ProAmatine(R), the
    combined company has a portfolio of five key products, each with
    significant sales potential. The additional resources and sales force
    coverage that the enlarged group will have are expected to help increase
    the sales potential of these products. The combined company will have a
    combined sales force of 269, 92 and 25 sales representatives in the U.S.,
    the U.K. and Canada, respectively. In addition, the merger broadens the
    therapeutic focus of Shire from the central nervous system,
    metabolic/bone disease and female health to include cardiovascular,
    gynecology/endocrinology, urology, oncology/hematology and
    gastroenterology. The proposed merger would reduce the percentage of
    total revenues contributed by Adderall(R) from approximately 70% for the
    first six months of 1999 to approximately 30% on a pro forma basis.

                                       51
<PAGE>

  .An enriched product pipeline. The combined company's key projects that are
    close to reaching market will include: Reminyl(R) (galantamine) for
    Alzheimer's disease, Dirame(R) (propiram) for analgesia, Emitasol(R)
    (nasal metoclopramide) for nausea, Lambda(R) (lanthanum carbonate) for
    hyperphosphatemia, and RL0903 (GnRH implant) for prostatic cancer. The
    combined company will have one product in registration and a further five
    products in Phase III.

  .Expected operating synergies. The proposed merger is expected to result in
    significant operating synergies, including elimination of certain
    duplicative costs; U.S. distribution synergies, including increased
    utilization of Roberts' new U.S. distribution center; and use of Shire's
    proprietary drug delivery technologies to fulfill the needs of certain of
    Roberts' products in development.

  .Strengthens geographic presence. The contemplated transaction will further
    strengthen Shire's presence in the U.S., the U.K. and Ireland. In
    addition, it will allow distribution of Shire products in Canada through
    Roberts' Canadian operations. The proposed combination will also allow
    the joint development of a continental European marketing infrastructure.
    The combined company intends to expand its direct marketing capability in
    continental Europe through a combination of product and company
    acquisitions.

  .Provides critical mass. The proposed merger will enhance the combined
    company's competitiveness through economies of scale and provide a strong
    platform for further growth from both existing pipeline products and
    product and company acquisitions. The transaction will combine
    complementary development and sales and marketing infrastructures,
    facilitating the development and distribution of pipeline products, as
    well as provide the combined company with greater negotiating leverage in
    pursuing licensing of products. In its chosen therapeutic areas, the
    combined company's aim is to become a "licensee of choice" for companies
    that do not possess their own sales and marketing capabilities.

  .Greater financial resources to pursue further growth opportunities. At
    June 30, 1999, Shire had no indebtedness and $79 million in cash and
    investments, while Roberts had approximately $130 million in indebtedness
    and $47 million in cash and investments. The merger will increase the
    combined company's ability to finance the acquisition of pipeline
    products and/or other companies and allow the pursuit of larger product
    and/or company acquisitions than could be pursued alone.

  .Increased investor profile and liquidity. Management believes that the
    combined company will benefit from a wider shareholder base and greater
    liquidity.

   In addition, the board considered the following factors:

  .Integration process. Roberts is a similar size to Shire and therefore
    presents a significant challenge in terms of integration. Substantial
    restructuring may be required, particularly in the U.S.

  .Non-prescription pharmaceuticals. Roberts owns a manufacturing facility in
    Canada and has a significant interest in non-prescription
    pharmaceuticals, neither of which conform to Shire's current strategic
    interests.

  .Loss of Foreign Private Issuer Status. After the merger, Shire will have
    the status of a full SEC registrant and will no longer benefit from
    foreign private issuer status.

   In addition to the aforementioned factors, the Shire board also considered
the key terms of the merger agreement, the option agreement, the shareholder
agreements and John T. Spitznagel's consulting agreement, as well as the
Roberts termination fee of $30 million contained in the merger agreement.
Consideration was also given to potential risks associated with the merger,
such as the ability to realize expected synergies, the lack of a fixed price
per Roberts share and the interests of various individuals in the merger.

Opinion of Financial Advisor to Roberts

   PaineWebber, as part of its engagement by Roberts, was retained to render an
opinion as to whether the merger consideration was fair, from a financial point
of view, to the holders of Roberts common stock. The

                                       52
<PAGE>

following is a summary of the report presented on July 22, 1999, by PaineWebber
to the Roberts board in connection with the rendering of its opinion.

   The full text of the PaineWebber opinion, dated July 22, 1999, which sets
forth the assumptions made, procedures followed, matters considered and
limitations on the review undertaken, is attached as Annex B to this
Prospectus-Proxy Statement. You should read the PaineWebber opinion carefully
and in its entirety. This summary of the PaineWebber opinion is qualified in
its entirety by reference to the full text of the PaineWebber opinion.

   In connection with the consideration by the Roberts board of the merger
agreement, PaineWebber delivered its written opinion, dated July 22, 1999, to
the effect that, as of that date, and based upon its review and assumptions and
subject to the limitations summarized below, the merger consideration is fair,
from a financial point of view, to the holders of Roberts common stock. The
PaineWebber opinion was directed to, and prepared at the request and for the
information of, the Roberts board and does not constitute a recommendation to
any holder of Roberts common stock as to how any such shareholder should vote
with respect to the merger.

   In arriving at its opinion, PaineWebber, among other things:

  .Reviewed, among other public information, Roberts' Annual Reports, Forms
    10-K and related financial information for the three fiscal years ended
    December 31, 1998; Roberts' Form 10-Q and the related unaudited financial
    information for the three months ended March 31, 1999; and certain
    unaudited financial information of Roberts for the six months ended June
    30, 1999.

  .Reviewed, among other public information, a Shire Annual Report and a
    Shire Transitional Report, each on Form 20-F and related financial
    information for the two fiscal years ended December 31, 1998; and certain
    unaudited financial information for the three months ended March 31,
    1999.

  .Reviewed certain information, including financial forecasts, relating to
    the business, earnings, cash flow, assets and prospects of Roberts and
    Shire, which, with respect to Roberts, were furnished to PaineWebber by
    or on behalf of Roberts and, with respect to Shire, were otherwise
    publicly available.

  .Conducted discussions with members of senior management of Roberts and
    Shire concerning their respective businesses and prospects.

  .Reviewed the historical market prices and trading activity for Roberts
    shares and Shire ordinary shares and ADSs and compared them with those of
    certain other publicly traded companies which PaineWebber deemed to be
    relevant.

  .Compared the financial position and operating results of Roberts and Shire
    with those of certain other publicly traded companies which PaineWebber
    deemed to be relevant.

  .Compared the financial terms of the merger with the financial terms of
    certain other business combinations which PaineWebber deemed to be
    relevant.

  .Reviewed a draft of the merger agreement dated July 21, 1999.

  .Reviewed a draft of the option agreement dated July 21, 1999.

  .Reviewed drafts of the shareholder agreements dated July 21, 1999.

  .Reviewed such other financial studies and analyses and performed such
    other investigations and took into account such other matters as
    PaineWebber deemed necessary, including PaineWebber's assessment of
    general economic, market and monetary conditions.

   In preparing its opinion, PaineWebber relied on the accuracy and
completeness of all information that was publicly available, supplied or
otherwise communicated to PaineWebber by or on behalf of Roberts and Shire, and
PaineWebber did not assume any responsibility to independently verify such
information. With respect to

                                       53
<PAGE>

the financial forecasts examined by PaineWebber, PaineWebber assumed, with
Roberts' consent, that they were reasonably prepared on bases reflecting the
best currently available estimates and good faith judgment of the management of
Roberts as to the future performance of Roberts. PaineWebber also relied upon
assurances of the management of Roberts and Shire that they were unaware of any
facts that would make the information or financial forecasts provided to
PaineWebber incomplete or misleading. PaineWebber was not engaged to make, and
did not make, an independent evaluation or appraisal of the assets or
liabilities (contingent or otherwise) of Roberts or Shire, nor was PaineWebber
furnished with any such evaluations or appraisals. PaineWebber also assumed the
following with Roberts' consent:

  .The merger will receive pooling-of-interests accounting treatment under
    U.S. GAAP.

  .The merger will qualify as a tax-free reorganization under U.S. tax law.

  .All material liabilities (contingent or otherwise, known or unknown) of
    Roberts and Shire were as set forth in the consolidated financial
    statements of Roberts and Shire, respectively.

   The PaineWebber opinion was based upon economic, monetary and market
conditions existing on the date of the PaineWebber opinion. Furthermore,
PaineWebber expressed no opinion as to the price or trading ranges at which
Roberts shares or Shire ordinary shares and ADSs will trade after the date of
the PaineWebber opinion. The PaineWebber opinion does not address the relative
merits of the merger and any other transactions or business strategies that may
have been discussed by the Roberts board of directors as alternatives to the
merger, or the decision of the Roberts board of directors to proceed with the
merger. PaineWebber was not requested to, and did not, solicit third party
indications of interest in acquiring all or any portion of Roberts. Roberts did
not place any limitations upon PaineWebber with respect to the procedures
followed or factors considered in rendering its opinion.

   The following paragraphs summarize the significant analyses performed by
PaineWebber in arriving at its opinion.

   Historical Share Performance. PaineWebber reviewed trading prices for the
shares of Roberts common stock. This share performance review indicated that
for the twelve months ended July 21, 1999, the low and high closing prices for
the Roberts shares on the American Stock Exchange were $15.94 and $26.88.
PaineWebber also reviewed the following Roberts share price averages over the
following periods prior to July 21, 1999 as set forth in the following table:

<TABLE>
<CAPTION>
            Trading Period                  Average Price
            --------------                  -------------
            <S>                             <C>
            Latest 10 days.................    $24.46
            Latest 20 days.................    $22.70
            Latest 30 days.................    $21.35
            Latest 60 days.................    $19.99
            Latest 180 days................    $21.23
            Latest twelve months...........    $20.87
</TABLE>

   PaineWebber also reviewed trading prices for the ADSs. This share
performance review indicated that for the twelve months ended July 21, 1999,
the low and high closing prices for the ADSs on the Nasdaq National Market were
$14.13 and $29.38. PaineWebber also reviewed the following Shire ADS price
averages over the following periods prior to July 21, 1999 as set forth in the
following table:

<TABLE>
<CAPTION>
            Trading Period                  Average Price
            --------------                  -------------
            <S>                             <C>
            Latest 10 days.................    $27.81
            Latest 20 days.................    $26.71
            Latest 30 days.................    $25.49
            Latest 60 days.................    $24.17
            Latest 180 days................    $22.27
            Latest twelve months...........    $21.76
</TABLE>

                                       54
<PAGE>

   Selected Comparable Public Company Analysis. Using publicly available
information, PaineWebber compared selected historical and projected financial,
operating and stock market performance data of Roberts and Shire to the
corresponding data of certain publicly traded companies that PaineWebber
deemed to be relevant for Roberts and Shire.

   The Roberts comparable companies consisted of:

<TABLE>
      <S>                                <C>
      Biovail Corporation International  King Pharmaceuticals, Inc.
      Dura Pharmaceuticals, Inc.         Medeva plc
      Forest Laboratories, Inc.          Medicis Pharmaceutical Corporation
      IVAX Corporation                   Watson Pharmaceuticals, Inc.
      Jones Pharma Incorporated
</TABLE>

   PaineWebber reviewed, among other information, the comparable companies'
multiples of total enterprise value, which consists of the market value of
equity plus total debt less cash and cash equivalents as of March 31, 1999 (as
of December 31, 1998 for Medeva plc), to:

  .latest twelve months revenue,

  .latest twelve months earnings before interest, taxes, depreciation and
    amortization, or EBITDA, and

  .latest twelve months earnings before interest and taxes, or EBIT.

   Multiples of total enterprise value represent the value of a particular
company as a measure of certain identified operating statistics. These
operating statistics include revenue, EBITDA and EBIT as described above.

   PaineWebber also reviewed, among other information, the comparable
companies' multiples of market value to:

  .latest twelve months net income,

  .calendar year 1999 earnings per share, or EPS estimate,

  .calendar year 2000 EPS estimate, and

  .calendar year 2001 EPS estimate.

   All calendar year 1999, 2000 and 2001 EPS results for the Roberts
comparable companies were based on publicly available consensus estimates from
First Call Research. Multiples of market value represent the value of a
particular company's equity as a multiple of certain identified operating
statistics. These operating statistics include net income and calendar year
1999, 2000 and 2001 EPS.

   The Roberts comparable companies analysis resulted in the following range
of values as of July 21, 1999:

<TABLE>
<CAPTION>
      Analysis                                                   Multiple Range
      --------                                                   --------------
      <S>                                                        <C>
      Latest twelve months revenue.............................. 1.52x to 12.17x
      Latest twelve months EBITDA...............................   5.0x to 35.1x
      Latest twelve months EBIT.................................   6.2x to 42.7x
      Latest twelve months net income...........................   7.7x to 64.2x
      Calendar year 1999 EPS estimate...........................  11.5x to 39.6x
      Calendar year 2000 EPS estimate...........................  10.7x to 26.3x
      Calendar year 2001 EPS estimate...........................   8.7x to 20.3x
</TABLE>

                                      55
<PAGE>

   Based on an exchange ratio of 1.1374 ADSs for each outstanding share of
Roberts common stock, Roberts' implied multiples, calculated on the same basis
as the Roberts comparable companies, were as follows:

<TABLE>
<CAPTION>
      Analysis                                          Roberts Implied Multiple
      --------                                          ------------------------
      <S>                                               <C>
      Latest twelve months revenue.....................          5.73x
      Latest twelve months EBITDA......................          19.1x
      Latest twelve months EBIT........................          24.2x
      Latest twelve months net income..................          39.7x
      Calendar year 1999 EPS estimate..................          35.0x
      Calendar year 2000 EPS estimate..................          26.2x
      Calendar year 2001 EPS estimate..................          14.8x
</TABLE>

   Calendar year 1999, 2000 and 2001 EPS for Roberts were based on estimates
provided by Roberts management.

   The shire comparable companies consisted of:

<TABLE>
      <S>                                <C>
      Biovail Corporation International  King Pharmaceuticals, Inc.
      Celltech Chiroscience plc          Medeva plc
      Dura Pharmaceuticals, Inc.         Medicis Pharmaceutical Corporation
      Forest Laboratories, Inc.          SkyePharma plc
      IVAX Corporation                   Watson Pharmaceuticals, Inc.
      Jones Pharma Incorporated
</TABLE>

   The Shire comparable companies analysis resulted in the following range of
values as of July 21, 1999:

<TABLE>
<CAPTION>
      Analysis                                                   Multiple Range
      --------                                                   ---------------
      <S>                                                        <C>
      Latest twelve months revenue.............................. 1.52x to 19.88x
      Latest twelve months EBITDA...............................   5.0x to 35.1x
      Latest twelve months EBIT.................................   6.2x to 42.7x
      Latest twelve months net income...........................   7.7x to 64.2x
      Calendar year 1999 EPS estimate...........................  11.5x to 39.6x
      Calendar year 2000 EPS estimate...........................  10.7x to 55.0x
      Calendar year 2001 EPS estimate...........................   8.7x to 20.3x
</TABLE>

   All calendar 1999, 2000 and 2001 EPS results for the Shire comparable
companies were based on publicly available consensus estimates from First Call
Research. Data for the latest twelve months were as of March 31, 1999 (as of
December 31, 1998 for Medeva plc and SkyePharma plc).

   Based upon the closing price of ADS on July 21, 1999 of $26.75, Shire's
implied multiples, calculated on the same basis as the Shire comparable
companies, were as follows:

<TABLE>
<CAPTION>
      Analysis                                              Shire Multiple Range
      --------                                              --------------------
      <S>                                                   <C>
      Latest twelve months revenue.........................        8.34x
      Latest twelve months EBITDA..........................        48.8x
      Latest twelve months EBIT............................        55.1x
      Latest twelve months net income......................        62.6x
      Calendar year 1999 EPS estimate......................        37.2x
      Calendar year 2000 EPS estimate......................        26.2x
      Calendar year 2001 EPS estimate......................        17.5x
</TABLE>

                                      56
<PAGE>

   The calendar year 1999, 2000 and 2001 EPS results for Shire were based on
publicly available estimates from First Call research

   Selected Comparable Mergers and Acquisitions Analysis.  PaineWebber reviewed
publicly available financial information for selected mertgers and
acquisiktions involving specialty and emerging pharmaceutical companies. The
selected mergers and acquisitions PaineWebber analyzed included the following:

<TABLE>
<CAPTION>
      Acquiror                 Target
      --------                 ------
      <S>                      <C>
      Johnson & Johnson        Centocor, Inc.
      Abbott Laboratories      Alza Corporation
      Solvay SA                 Unimed Pharmaceuticals, Inc.
      Warner-Lambert Company    Agouron Pharmaceutical, Inc.
      Watson Pharmaceuticals,
       Inc.                     TheraTech, Inc.
      Mylan Incorporated        Penederm Incorporated
      Cardinal Health, Inc.     R.P. Scherer Corporation
      Alpharma Inc.             Arthur Cox (Hoechst AG)
      Elan Corporation, plc     Carnrick Laboratories, Inc. (GWC Health, Inc.)
      Abbott Laboratories       MediSense, Inc.
      Rhone Poulenc Rorer      Fisons plc
      Watson Pharmaceuticals,
       Inc.                    Circa Pharmaceutical Incorporated
      Hoechst AG               Marion Merrell Dow
      Roche Holding AG         Syntex Corporation
</TABLE>

   PaineWebber reviewed the consideration paid based on the offer price of
comparable transactions and calculated multiples of total enterprise value. The
comparable transactions analysis resulted in the following range of values:

<TABLE>
<CAPTION>
      Analysis                                                   Multiple Range
      --------                                                  ----------------
      <S>                                                       <C>
      Latest twelve months revenue.............................   1.54x to 36.8x
      Latest twelve months EBITDA..............................    9.4x to 66.2x
      Latest twelve months EBIT................................  11.3x to 104.9x
      Latest twelve months net income.......................... 13.8x to 1777.0x
      One year forward EPS.....................................   175x to 120.0x
      Two year forward EPS.....................................   16.0x to 87.8x
</TABLE>

   The one year and two year forward EPS were based on publicly available
consensus estimates from First Call Research.

   Based on an exchange ratio of 1.1374 ADSs for each outstanding share of
Roberts common stock, Roberts' implied multiples, calculated on the same basis
as the comparable transactions, were as follows:

<TABLE>
<CAPTION>
      Analysis                                          Roberts Implied Multiple
      --------                                          ------------------------
      <S>                                               <C>
      Latest twelve months revenue.....................          5.73x
      Latest twelve months EBITDA......................          19.1x
      Latest twelve months EBIT........................          24.2x
      Latest twelve months net income..................          39.7x
      One year forward EPS.............................          35.0x
      Two year forward EPS.............................          26.2x
</TABLE>

   One year forward and two year forward EPS for Roberts were based on
estimates provided by Roberts management.

                                       57
<PAGE>

   Discounted Cash Flow Analysis.  PaineWebber analyzed Roberts based on an
unleveraged discounted cash flow analysis of the projected financial
performance of Roberts. Such projected financial performance was based upon a
forecast for Roberts provided by Roberts management. The discounted cash flow
analysis determined the discounted present value of the unleveraged after-tax
cash flows generated over the forecast period and then added a terminal value
based upon a range of revenue and EBITDA multiples and discount rates which
PaineWebber deemed appropriate.

   Premiums Paid Analysis. PaineWebber reviewed purchase price per share
premiums paid in publicly disclosed merger transactions of non-financial
domestic companies announced and completed from January 1, 1998 to July 16,
1999. This analysis indicated the following premiums to the targets' closing
stock prices:

<TABLE>
<CAPTION>
      Period prior to announcement                                High    Low
      ----------------------------                                -----  -----
      <S>                                                         <C>    <C>
      One day.................................................... 114.3% (11.2)%
      One week................................................... 139.2% (14.4)%
      Four weeks................................................. 185.9% (16.9)%
</TABLE>

   PaineWebber also reviewed the purchase price per share premiums paid in the
comparable transactions described in the "Selected comparable mergers and
acquisitions analysis" above. This analysis indicated the following premiums to
the targets' closing stock prices as set forth in the following table:

<TABLE>
<CAPTION>
      Period prior to announcement                                High    Low
      ----------------------------                                -----  -----
      <S>                                                         <C>    <C>
      One day....................................................  61.1% (10.3)%
      One week...................................................  81.1%  (4.2)%
      Four weeks................................................. 185.9%  (8.3)%
</TABLE>

   The implied premiums to Roberts closing share price based on an implied
exchange ratio of 1.1374 ADSs per Roberts share for the one day, one week and
four week periods prior to July 21, 1999 were as set forth in the following
table:

<TABLE>
<CAPTION>
                                                                 Roberts Implied
      Period prior to July 21, 199                                   Premium
      ----------------------------                               ---------------
      <S>                                                        <C>
      One day...................................................      38.3%
      One week..................................................      22.9%
      Four weeks................................................      58.1%
</TABLE>

   Contribution Analysis. PaineWebber analyzed Roberts' and Shire's relative
contribution to the combined entity, based on Roberts' management projections
and publicly available estimates for Shire, for the fiscal years 1999 and 2000
with respect to revenue, EBIT and net income, as set forth in the following
table:

<TABLE>
<CAPTION>
                                                            Roberts Contribution
      Analysis                                              to Pro Forma Entity
      --------                                              --------------------
      <S>                                                   <C>
      1999
      Revenue..............................................         46.9%
      EBIT.................................................         51.3%
      Net income...........................................         66.2%
      2000
      Revenue..............................................         44.6%
      EBIT.................................................         49.4%
      Net income...........................................         50.0%
</TABLE>

   Based on an exchange ratio of 1.1374 ADSs for each outstanding share of
Roberts common stock, holders of Roberts shares will own approximately 44.0% of
the outstanding shares of the combined entity after giving effect to the
merger.

                                       58
<PAGE>

   The results of this contribution analysis are not necessarily indicative of
the contributions that the respective businesses of Roberts and Shire may make
to the combined entity in the future.

   Pro Forma Merger Analysis. PaineWebber performed an analysis of the
potential pro forma effect of the merger on Shire's projected EPS. In
performing this analysis, PaineWebber assumed the following with Roberts'
consent:

  .The merger will be accounted for under U.S. GAAP pooling-of-interests
    accounting treatment.

  .Reconciliation of Shire's financial results to U.S. GAAP.

  .Certain synergies may be achieved as a result of the merger.

   PaineWebber combined the projected operating results of Roberts provided by
Roberts management with publicly available estimates for Shire, adjusted to
U.S. GAAP, to arrive at the combined company projected net income. PaineWebber
divided this result by the pro forma diluted shares outstanding to arrive at a
combined company diluted EPS amount. PaineWebber then compared the calculated
combined company EPS to the EPS estimate for Shire on a stand-alone basis to
determine the pro forma impact of the merger on Shire.

   The summary of the PaineWebber opinion set forth above does not purport to
be a complete description of the data or analyses presented by PaineWebber. The
preparation of a fairness opinion involves various determinations as to the
most appropriate and relevant quantitative methods of financial analyses and
the application of those methods to the particular circumstances and,
therefore, such an opinion is not readily susceptible to partial analysis or
summary description. Accordingly, PaineWebber believes that its analysis must
be considered as a whole and that considering any portion of such analysis and
of the factors considered, without considering all analyses and factors, could
create a misleading or incomplete view of the process underlying the opinion.
In its analyses, PaineWebber made numerous assumptions or estimates with
respect to industry performance, general business and economic conditions and
other matters, many of which are beyond the control of Roberts and Shire. Any
assumptions or estimates contained in these analyses are not necessarily
indicative of actual values or predictive of future results or values, which
may be significantly more or less favorable than as set forth therein.
Accordingly, such assumptions or estimates are inherently subject to
substantial uncertainty and neither Roberts nor PaineWebber can guarantee the
accuracy of such assumptions or estimates. In addition, analyses relating to
the value of businesses do not purport to be appraisals or to reflect the
prices at which businesses may actually be sold.

   Roberts selected PaineWebber to be its financial advisor in connection with
the merger because PaineWebber is a prominent investment banking and financial
advisory firm with experience in the valuation of businesses and their
securities in connection with mergers and acquisitions, negotiated
underwritings, secondary distributions of securities, private placements and
valuations for corporate purposes.

   Pursuant to an engagement letter between Roberts and PaineWebber dated May
29, 1998, PaineWebber earned a fee of $750,000 for rendering the opinion. In
addition, PaineWebber will receive a fee, payable upon completion of the
merger, of approximately $6.2 million, and will be reimbursed for certain of
its related expenses. PaineWebber will not be entitled to any additional fees
or compensation in the event the merger is not approved or otherwise
consummated. Roberts also agreed, under separate agreement, to indemnify
PaineWebber, its affiliates and each of its directors, officers, agents and
employees and each person, if any, controlling PaineWebber or any of its
affiliates against certain liabilities, including liabilities under U.S.
federal securities laws.

   In the ordinary course of business, PaineWebber may actively trade the
securities of Roberts and Shire for its own account and for the accounts of its
customers and, accordingly, may at any time hold long or short positions in
such securities.

                                       59
<PAGE>

Interests in the Merger of Persons Affiliated with Roberts

   General. Some members of Roberts' senior management and the Roberts board
may be deemed to have interests in the merger that are in addition to and/or
potentially different from the interests of shareholders of Roberts generally.
The Roberts board was aware of these interests and considered them, among other
matters, in approving the merger agreement and the transactions contemplated by
the merger agreement. In considering the recommendations of the Roberts board
in respect of the merger agreement and the transactions contemplated by the
merger agreement, the Roberts shareholders should be aware that these interests
may present actual or potential conflicts of interest with respect to the
merger.

   Shire Board Appointments. Shire has agreed, except as limited by the
exercise of fiduciary duties and to the extent permitted by law, to cause Dr.
Robert Vukovich, Chairman of the Board of Roberts, John T. Spitznagel, Chief
Executive Officer and a director of Roberts, and Dr. Zola Horovitz, Ronald
Nordmann and Joseph Smith, each a director of Roberts, to be appointed as non-
executive directors of Shire following the merger. These appointees will fill
five of the eleven directorships which Shire will have immediately after the
merger.

   Senior Management Employment Agreements. Under the terms of employment
agreements with Messrs. Spitznagel, Loy, Rascio, Rogalin, Berardi and Tierney,
in the event that their employment is terminated following a change of control
other than for the officer's willful misconduct, the officer is entitled to
receive severance compensation of:

  .base compensation, at the annual rate at the time of termination, for
    three years, or four years in the case of Mr. Spitznagel, after the
    termination,

  .additional payments equal to three times, or four times in the case of Mr.
    Spitznagel, the greater of $50,000 or the officer's average annual bonus
    and incentive compensation for the period commencing March 4, 1996 in the
    case of Mr. Spitznagel, August 31, 1992 in the case of Mr. Loy, July 1,
    1988 in the case of Mr. Rascio, February 5, 1996 in the case of Mr.
    Rogalin, November 3, 1997 in the case of Mr. Berardi and April 8, 1997 in
    the case of Dr. Tierney, and ending upon the termination of employment,
    and

  .an amount equal to three times, or four times in the case of Mr.
    Spitznagel, any payment made by Roberts to the 401(k) Plan on behalf of
    the officer during the fiscal year prior to termination.

   Following a change in control of Roberts, each of Messrs. Spitznagel, Loy,
Rogalin, Rascio, Berardi and Tierney has the right to terminate his employment
agreement and receive the full amount of his severance compensation, if he
remains in the employ of Roberts or any successor thereto for a period of one
(1) year following a change in control and provides Roberts with notice of
termination during the thirty (30) day period immediately following the end of
the one (1) year period, or at any time after the change in control if his
duties are diminished, his place of employment is relocated more than twenty
(20) miles from its prior location, or his annual compensation is reduced. The
merger constitutes a change in control for purposes of these agreements.

   The Internal Revenue Code of 1986, as amended, imposes an excise tax on and
limits Roberts' deduction of payments to employees whose employment has been
terminated following a change in control if the payments meet certain
requirements and exceed the limit set forth in the Code. Generally, this limit
is equal to three times the employee's average annual compensation for the five
taxable years preceding the year in which the change of control occurs. The
employment agreements with Messrs. Spitznagel, Loy, Rogalin, Rascio, Berardi
and Tierney provide that Roberts shall pay any excise taxes assessed against
the officers in connection with any severance compensation payments made or
benefits conferred under the employment agreements, including, in connection
with a change in control of Roberts. In March 1999, the Roberts board
authorized amendments to each of the employment agreements with Messrs.
Spitznagel, Loy, Rogalin, Rascio, Berardi and Tierney to provide that Roberts
shall pay any and all income taxes, including excise taxes, incurred by them as
a result of their receiving payments to cover the additional income and excise
taxes.

                                       60
<PAGE>

   In the event of the termination of an officer's employment with Roberts for
any reason, each of these employment agreements provides that the officer shall
have the right to elect, during the one year period after the date of
termination, to exercise all options previously granted to the officer under
all stock option plans maintained by Roberts, regardless of whether the options
would then be exercisable. The current terms of each of the employment
agreements, which are automatically renewed for successive one year periods
upon their expiration, expire on August 31, 2001, with the exception of Mr.
Spitznagel's employment agreement which expires on August 31, 2002.

   Retention Agreements. Roberts has retention agreements with ten senior
executives, other than the six identified above, providing that in the event:

  .Roberts terminates the employment of the executive following a "change of
    control," as defined in each retention agreement,

  .the executive terminates his or her employment during the thirty day
    period following the first anniversary of the change of control, or

  .the executive terminates his or her employment following a change of
    control for certain specified reasons such as diminution in duties or
    compensation or relocation,

then the executive shall be entitled to receive an award for service equal to
the executive's annual compensation at the time of termination and an amount
equal to the executive's incentive bonus for the year immediately preceding the
year in which the executive's employment was terminated. In the event of the
termination of an officer's employment with Roberts for any reason, each of
these retention agreements provides that the executive shall have the right to
elect, during the one year period after the date of termination, to exercise
all options previously granted to the executive under all stock option plans
maintained by Roberts, regardless of whether the options would then be
exercisable. The merger constitutes a change of control for purposes of the
retention agreements.

   Employee Severance Policy. Roberts has adopted a Change of Control Severance
Plan covering all employees who are not parties to employment agreements or
retention agreements. The severance plan provides that a participant in the
plan would receive, in the event of a termination by Roberts "without cause" or
by a participant for "good reason" within two years following a "change of
control," each as defined in the severance plan:

  .continuation of base salary following termination of employment for a
    length of time equal to the sum of three weeks for each complete year of
    service with Roberts and three weeks for any partial year of service in
    which the participant was employed for more than 6 months;

  .any accrued but unpaid base salary through the date of termination;

  .any actual earned annual bonus for any completed year which has not yet
    been paid;

  .the participant's average target bonus for the year of termination,
    prorated through his or her date of termination; and

  .a payment in respect of accrued vacation and sick pay.

In addition, the severance plan provides that Roberts would continue to provide
the participant with medical and dental benefits for the participant and his or
her eligible dependents during the period in which the plan participant is paid
severance benefits and would provide outplacement services for the participant
at a cost of up to 10% of the participant's base salary. The severance plan
provides that it may not be amended or terminated within two years following a
change of control. The merger constitutes a change of control for purposes of
the severance plan.

   1996 Equity Incentive Plan. All options granted under the 1996 Equity
Incentive Plan will vest and be fully exercisable upon completion of the
merger.

                                       61
<PAGE>

   Supplemental Executive Retirement Plan. The Roberts Supplemental Executive
Retirement Plan provides certain protections for Messrs. Spitznagel, Loy,
Rogalin, Rascio, Berardi and Tierney following a "change of control," as
defined in the plan. The plan provides that upon a change of control, each
participant shall become fully vested and each participant shall be given
credit for 10 years of service with Roberts. In addition, the plan provides
that upon a change of control, Roberts shall fund a grantor trust with
sufficient assets to pay each participant his accrued benefits under the plan.
The merger constitutes a change of control for purposes of the plan.

   John T. Spitznagel Consulting Agreement. It is expected that Shire will
enter into a consulting agreement with Mr. Spitznagel shortly following the
merger. The consulting agreement is expected to provide that:

  .Mr. Spitznagel will have "good reason" to terminate his employment with
    Roberts under his employment agreement and that Shire will cause Roberts
    to provide him with the payments and benefits he is entitled to upon a
    "good reason" termination;

  .Mr. Spitznagel will provide consulting services to Shire for at least 42
    months following the merger, unless he terminates the agreement prior to
    the end of the 42nd month upon 30 days' notice; and

  .Shire will pay Mr. Spitznagel at a rate of $400,000 per annum for his
    consulting services, $150,000 per annum as an office allowance, $250,000
    per annum to comply with certain restrictive covenants contained therein,
    and $140,000 per annum for tax, financial and estate planning advice,
    life insurance and health insurance.

The consulting agreement is expected to include a number of restrictive
covenants, including a non-compete/non-solicitation provision running for the
life of the consulting agreement and 12 months thereafter and a confidentiality
provision.

   Director and Officer Indemnification and Insurance. Shire has agreed that
until the sixth anniversary of the merger, it will indemnify, defend and hold
harmless anyone who served as an officer or director of Roberts or any of its
subsidiaries against or from all losses, claims, damages and expenses,
including attorneys' fees, arising out of actions or omissions occurring at any
time before the merger to the same extent permitted or required by the existing
provisions for indemnification of officers and directors of Roberts contained
in the certificates of incorporation and by-laws of Roberts and its
subsidiaries. Furthermore, Shire has agreed that, until the sixth anniversary
of the merger, it will cause to be maintained in effect the policies of
directors' and officers' liability insurance maintained by Roberts and its
subsidiaries as of the date of the merger agreement with respect to claims
arising from facts or events that occurred on or before the merger.

   401(k) Plan. Under the Employee Savings and Protection Plan, or the 401(k)
Plan, for all employees of Roberts who are employed as of December 31 of each
year, Roberts may, in its discretion, contribute a percentage of each
employee's salary or wages paid that year into each employee's 401(k) Plan
account, whether the employee is making elective contributions to the 401(k)
Plan or not. Historically, Roberts has contributed 2% of each employee's salary
or wages paid that year. The merger agreement states that employees who are
employed at the time of the merger shall receive 2% of their salary or wages
for the 1999 calendar year, notwithstanding their employment status on December
31, 1999.

Dissenters' Rights

   In accordance with Chapter 11 of the New Jersey Business Corporation Act, no
holder of Roberts shares shall be entitled to dissenters' rights.

Other Effects of the Merger

   It is a condition to the merger that the LSE shall have admitted to the
Official List (subject to allotment) the Shire ordinary shares to be allotted
by Shire in connection with the merger and that such admission shall

                                       62
<PAGE>

have become effective in accordance with the rules and regulations of the LSE.
It is also a condition to the merger that the Shire ADSs to be issued in the
merger shall have been approved for listing on Nasdaq. If the merger is
consummated, Roberts shares will cease to be listed on the Amex. For
information concerning the income tax consequences of the ownership of Shire
ADSs, see "Certain Tax Consequences." Following the merger, Roberts will cease
filing periodic reports with the SEC under the Exchange Act.

Governmental Regulation

 U.S. Antitrust

   Under the Hart-Scott-Rodino Antitrust Improvements Act of 1976, as amended,
and the rules promulgated thereunder, certain transactions, including the
merger, may not be consummated unless certain waiting period requirements have
been satisfied. On August 10, 1999, Roberts and Shire each filed a Pre-merger
Notification and Report Form in accordance with the provisions of the Hart-
Scott-Rodino Act with the Antitrust Division and the FTC. The required waiting
period expired on September 10, 1999.

 Exon-Florio

   The provisions of Exon-Florio promulgated under the Omnibus Trade and
Competitiveness Act of 1988 empower the President of the United States to
prohibit or suspend an acquisition of, or investment in, a U.S. company by a
foreign person if the President finds, after investigation, credible evidence
that the foreign person might take action that threatens to impair the national
security of the U.S. and that other provisions of existing law do not provide
adequate and appropriate authority to protect the national security. Any
determination that an investigation is called for must be made within 30 days
of notice of the proposed transaction. In the event such a determination is
made, any such investigation must be completed within 45 days of such
determination. Thereafter, any decision to take action must be announced within
15 days of completion of the investigation. Authority under these provisions
has been delegated to the Committee on Foreign Investment in the United States.
On October 21, 1999, Roberts and Shire made a voluntary filing to this
committee seeking a finding that the merger does not impair the national
security of the U.S.

 U.K. Antitrust

   In the U.K., the Secretary of State can refer any qualifying merger
situation to the Competition Commission for investigation as to whether the
merger may be expected to operate against the public interest. The merger of
Roberts and Shire is a qualifying merger situation for the purposes of U.K.
law. There is no obligation to obtain prior clearance of a qualifying merger in
the U.K. However, if a qualifying merger is completed without prior clearance
being given, there is a risk that the merger may subsequently be referred to
the Competition Commission and that divestments might ultimately be required.

   No submission has been made to the U.K. authorities in relation to the
merger, but on July 26, 1999, Shire received from the U.K. Office of Fair
Trading a letter requesting various general information about the businesses of
Shire and Roberts. A response to that letter was provided on July 29 and was
followed by subsequent communications. On October 18, 1999, the Office of Fair
Trading confirmed that the merger had been cleared.

Anticipated Accounting Treatment and Effects

   The merger is intended to qualify as a pooling of interests transaction
under U.S. GAAP, which means the recorded assets and liabilities of Roberts
will be carried forward to the combined business at their recorded amounts. The
historical revenues and expenses of Roberts, for all periods, will be combined
with those of Shire, whose financial statements will then be restated. The
merger will be accounted for as a purchase under U.K. GAAP, which, based on the
Shire ADS price as of July 21, 1999 and the Roberts balance sheet as of
June 30, 1999, will produce goodwill of approximately $700 million that will be
amortized over 20 years.

                                       63
<PAGE>

                          DESCRIPTION OF INDEBTEDNESS

   Roberts is a party to a credit agreement, dated as of June 24, 1998, among
itself, DLJ Capital Funding, Inc. and various other lenders. The outstanding
indebtedness under this credit agreement is $125 million. The interest rate per
annum is calculated as the 30 Day LIBOR rate plus 2%, which as of October 14,
1999 is 7.45% per annum. The funds provided under this credit agreement
financed Roberts' acquisition of its Pentasa(R) product. Pursuant to the terms
of the credit agreement, a change of control of Roberts is an event of default
permitting the lenders to accelerate payment of the principal amount
outstanding. The merger constitutes a change of control under the credit
agreement. Roberts and Shire's United States subsidiaries, as borrowers, and
Shire entered into an agreement dated November  , 1999, to replace the existing
credit facility with a $250 million credit facility consisting of a $125
million five-year revolving credit facility (including a $25 million letter of
credit facility) and a $125 million five-year term loan facility. The
applicable interest rate on the new credit facility will range between 1.00%
and 2.00% over the higher of DLJ's prime rate or the Federal Funds Rate or
between 1.50% and 2.50% over the London Interbank Overnight rate, in each case
depending on Shire's credit rating. All obligations under the new credit
facility will be jointly and severally guaranteed by Shire and by all of
Shire's subsidiaries (other than the borrowers) and will initially be secured
by all material property owned by Shire and its subsidiaries and the capital
stock of Shire's subsidiaries. If Shire's credit rating reaches specified
levels, the new credit facility will not be secured.


   The new credit facility will contain customary covenants, including
restrictions on:

  .debts and liens;

  .the sale of assets;

  .mergers and acquisitions;

  .transactions with affiliates;

  .sales and leaseback transactions;

  .loans and investments; and

  .capital expenditures.

   The terms of the credit agreement will also contain maintenance tests which
will require Shire to maintain a minimum net worth, a specified leverage ratio
and a specified coverage ratio.

                                       64
<PAGE>

                              THE MERGER AGREEMENT

   The following description of the material provisions of the merger agreement
is only a summary and does not purport to be complete. This description is
qualified in its entirety by reference to the merger agreement, a copy of which
is attached to this Prospectus-Proxy Statement as Annex A and is incorporated
herein by reference.

General; Effective Time and Effects of the Merger

   The merger agreement provides that, subject to the approval of the merger
agreement by the affirmative vote of at least two-thirds of the votes cast by
the holders of Roberts shares present or represented by proxy at the special
meeting and a majority of the shareholders of Shire voting at the meeting to be
convened of Shire shareholders and the satisfaction or waiver of other
conditions to the merger, Ruby Acquisition Sub will be merged with and into
Roberts, with Roberts continuing as the surviving corporation and as a wholly-
owned subsidiary of Shire.

   If the merger agreement is approved by the shareholders of Roberts and
Shire, and the other conditions to the merger are satisfied or, where
permissible, waived, the effective time will occur at the time of filing of a
certificate of merger with the Secretary of State of the State of New Jersey.
At the effective time, the certificate of incorporation and by-laws of Roberts,
as in effect immediately prior to the effective time, will be the certificate
of incorporation and by-laws of the surviving corporation until thereafter
changed or amended as provided therein or by applicable law.

Directors of Shire Immediately Following the Merger

   The newly combined board of directors of Shire will be comprised of eleven
members, six from Shire's current board and five from Roberts' current board:

<TABLE>
       <S>                  <C>
       Dr. James Cavanaugh  Non-executive Chairman
       Rolf Stahel          Chief Executive
       Stephen Stamp*       Group Finance Director
       Dr. Wilson Totten    Group R&D Director
       Dr. Bernard Canavan  Non-executive
       Dr. Zola Horovitz    Non-executive
       Ronald Nordmann      Non-executive
       Dr. Barry Price      Non-executive
       Joseph Smith         Non-executive
       John T. Spitznagel   Non-executive
       Dr. Robert Vukovich  Non-executive
</TABLE>
- --------
* On October 29, 1999, Shire announced that on December 13, 1999, Stephen Stamp
  will be replaced as Group Finance Director by Angus Russell.

Conversion of Roberts Shares

   The merger agreement provides that, as of the effective time, by virtue of
the merger and without any action on the part of any Roberts shareholder:

  . each share of Roberts common stock issued and outstanding immediately
    prior to the effective time will be converted into the right to receive
    either ordinary shares or ADSs; this does not include any shares of
    Roberts common stock owned by Roberts or Shire or by any of their
    subsidiaries;

  . each share of common stock of Ruby Acquisition Sub issued and outstanding
    immediately prior to the effective time will be canceled;

                                       65
<PAGE>

  .  each share of Roberts common stock that is owned by Roberts or Shire or
     by any of their subsidiaries will be canceled and retired and will cease
     to exist; and

  .  each Roberts shareholder will receive, for each share of Roberts common
     stock held by it:

   -- a fixed exchange ratio of 3.4122 ordinary shares if the average
      closing price of the ADSs for the 15 consecutive trading days ending
      the third trading day prior to closing is equal to or greater than
      $23.73 and less than or equal to $29.01;

   -- a floating exchange ratio between approximately 3.4122 and
      approximately 3.1280 if the average closing price is greater than
      $29.01 and less than or equal to $31.65 (equivalent to $33.00 per
      Roberts share);

   -- a floating exchange ratio between approximately 3.8407 and
      approximately 3.4122 if the average closing price is equal to or
      greater than $21.09 and less than $23.73 (equivalent to $27.00 per
      Roberts share);

   -- a fixed exchange ratio of 3.8407 if the average closing price is below
      $21.09; and

   -- a fixed exchange ratio of 3.1280 if the average closing price is
      greater than $31.65.

   Shire will provide each Roberts shareholder with one-third of an ADS for
each ordinary share such holder would be entitled to receive unless such
shareholder elects to receive ordinary shares.

                                       66
<PAGE>

The Exchange Ratio

   The chart below sets forth a range of possible average closing prices for
the ADSs, the corresponding exchange ratio for ADSs to be received in the
merger and the equivalent market value per share of Roberts common stock
assuming that an ADS had a value equal to the average closing price. The
exchange ratio will be determined based on the average ADS trading price at the
close of the market during the 15 trading days ending the third trading day
before the merger is completed. The average closing prices set forth below are
for illustrative purposes and are not intended to be an exhaustive list of
possible average closing prices. On the date a holder of Roberts common stock
receives ADSs, they may have a value equal to, greater than or less than the
equivalent values set forth below.

Average Closing Price, Exchange Ratio and Equivalent Value

<TABLE>
<CAPTION>
                                 Calculated Average
                                    Trading Price
                                       per ADS
                                 (one ADS represents   ADS    Hypothetical Value
                                   three ordinary    Exchange  for Each Roberts
                                       shares)        Ratio         Share
                                 ------------------- -------- ------------------
   <S>                           <C>                 <C>      <C>
                                        20.00         1.2802        25.60
                                        20.50         1.2802        26.25
                                        21.00         1.2802        26.89
   Fixed Price..................        21.50         1.2558        27.00
                                        22.00         1.2273        27.00
                                        22.50         1.2000        27.00
                                        23.00         1.1739        27.00
   Fixed Price..................        23.50         1.1489        27.00
                                        24.00         1.1374        27.30
                                        24.50         1.1374        27.87
                                        25.00         1.1374        28.44
                                        25.50         1.1374        29.00
                                        26.00         1.1374        29.57
                                        26.50         1.1374        30.14
                                        27.00         1.1374        30.71
                                        27.50         1.1374        31.28
                                        28.00         1.1374        31.85
                                        28.50         1.1374        32.42
                                        29.00         1.1374        32.98
   Fixed Price..................        29.50         1.1186        33.00
                                        30.00         1.1000        33.00
                                        30.50         1.0820        33.00
                                        31.00         1.0645        33.00
   Fixed Price..................        31.50         1.0476        33.00
                                        32.00         1.0427        33.37
                                        32.50         1.0427        33.89
                                        33.00         1.0427        34.41
</TABLE>

   If the ADS price is below $20.00, the exchange ratio remains at 1.2802 and
the hypothetical value for each Roberts share will be lower than the value
presented in the table. If the ADS price is above $33.00, the exchange ratio
remains at 1.0427 and the hypothetical value for each Roberts share will be
higher than the value presented in the table.

   We do not know what the market prices of Roberts common stock or ADSs will
be at the effective time or during the period in which the average closing
price is calculated. Because the exchange ratio is based on an average of the
closing price of the ADSs for a period prior to the effective time, the market
price of the Roberts

                                       67
<PAGE>

common stock at the effective time may be less than, equal to or greater than
the average closing price for the ADSs. The market value of the ADSs that
holders of Roberts common stock will receive upon consummation of the merger
may vary significantly from the market value of the ADSs that holders of
Roberts common stock would receive if the merger was consummated and holders of
Roberts common stock received ADSs on the date of this Prospectus-Proxy
Statement or on the date of the special meeting.

No Fractional ADSs or Ordinary Shares

   No fractional ADSs or ordinary shares will be issued in the merger. Instead,
each holder of Roberts common stock who otherwise would be entitled to receive
a fractional ADS or ordinary share will be paid an amount in cash, without
interest, in an amount equal to such fraction multiplied with respect to ADSs,
by the last reported sale price of the ADSs on Nasdaq on the trading day
immediately following the closing date, and with respect to ordinary shares, by
the latest closing mid-market price of the ordinary shares on the trading day
immediately following the closing date.

Exchange of Share Certificates

   At the effective time, Shire will deposit, in trust, with Morgan Guaranty
Trust Company of New York, as exchange agent, for the benefit of the holders of
Roberts common stock, that number of ordinary shares issuable in exchange for
Roberts common stock.

   As soon as practicable after the effective time, the exchange agent will
mail to each record holder of a certificate or certificates, which immediately
prior to the effective time represented outstanding Roberts common stock:

  .  a letter of transmittal which specifies that delivery will be effected,
     and risk of loss and title to the certificates shall pass, only upon
     proper delivery of the certificates to the exchange agent; and

  .  instructions for use in effecting the surrender of the certificates in
     exchange for the merger consideration.

   Upon surrender to the exchange agent of a certificate for cancellation,
together with a properly executed letter of transmittal, and other documents as
may be reasonably required pursuant to the instructions to the letter of
transmittal, in exchange for such certificates, the holder will be entitled to
receive the merger consideration.

Treatment of Roberts Stock Options

   At the effective time, Shire will assume each of Roberts' stock option plans
and all options will be adjusted so that each holder of an option will have
such option apply to that number of ordinary shares (adjusted to the nearest
whole share) equal to the product of the number of all options of such optionee
immediately prior to the effective time and the exchange ratio. The exercise
price per share for each option assumed, adjusted to the nearest pence, will
equal the old exercise price per Roberts share divided by the exchange ratio,
except for incentive stock options, which will be adjusted in order to continue
the qualification of those options as "incentive stock options" under U.S. tax
laws. The duration and other terms of each assumed or replaced option
immediately after the effective time will be the same as the corresponding
options that were in effect immediately before the effective time.

   As of the record date, approximately 3,151,048 shares of Roberts common
stock were issuable upon the exercise of outstanding Roberts options. Such
Roberts options will be converted at the effective time into Shire ordinary
share options.

                                       68
<PAGE>

Employee Benefits and Options

   In the merger agreement, Shire has agreed:

  .  that until December 31, 2001, it will maintain wages, compensation
     levels, employee pension and welfare plans that are, in the aggregate,
     equal or greater in value than those wages, compensation levels and
     other benefits that were in effect prior to the date of the merger
     agreement;

  .  that it will pay bonuses up to $1,500,000 for calendar year 1999 to
     Roberts employees and up to $1,000,000 to its four corporate officers;
     and

  .  that it will assume or replace all options issued under Roberts' stock
     option plans so that each holder of an option shall have such options
     apply to that number of ordinary shares equal to the number of options
     held by the holder multiplied by the exchange ratio. The exercise price
     for the options will be adjusted such that, in the aggregate, the option
     holder will pay the same amount for Shire ordinary shares as would have
     been paid for the Roberts shares.

Indemnification and Insurance

   In the merger agreement, Shire has agreed that, after the effective time, it
will indemnify all directors and officers or Roberts for all losses with
respect to actions or omissions by them on or prior to the merger and that
Shire will, for a period of six years after the effective time, maintain in
effect Roberts' directors' and officers' liability insurance with respect to
acts or omissions occurring prior to the merger covering each person currently
covered by Roberts' directors' and officers' liability insurance.

Representations and Warranties

   The merger agreement contains customary representations and warranties made
by Roberts and Shire with respect to, among other things:

  .  due organization and good standing;

  .  capitalization;

  .  corporate authority to enter into the contemplated transactions;

  .  lack of conflicts with corporate governance documents;

  .  reports and financial statements;

  .  absence of certain changes or events;

  .  compliance with law;

  .  brokers or finders;

  .  absence of litigation;

  .  filing of tax returns;

  .  absence of labor complaints;

  .  environmental matters; and

  .  marketing practices.

Conduct of Business Pending Merger

   During the period from the date of the merger agreement and continuing until
the effective time, each of Roberts and Shire has agreed as to itself and its
subsidiaries that, among other things it and its subsidiaries will carry on
their respective businesses only in the ordinary course and will use reasonable
efforts to maintain and preserve its business organization, assets, employees
and business relationships and to maintain all of its properties and assets in
useful and good condition.

                                       69
<PAGE>

   The merger agreement contains certain other covenants of Roberts and Shire
relating to the conduct of their respective businesses before the effective
time, including:

  .  covenants relating to the declaration and payment of dividends and
     changes in share capital;

  .  the issuance of securities;

  .  the amendment of corporate governance documents;

  .  the incurrence of indebtedness and the acquisition of equity interests;

  .  the maintenance of benefits plans and compensation;

  .  the entering into of material agreements; and

  .  the preservation of the availability of pooling-of-interests accounting
     treatment.

No Solicitation

   According to the terms of the merger agreement, Roberts and Shire have each
agreed that, prior to the effective time, neither it, any of its affiliates,
nor any of the respective directors, officers, employees, agents or
representatives of the foregoing, will:

  . solicit or initiate, including by way of furnishing or disclosing non-
    public information, any inquiries or the making of any proposal with
    respect to any merger, consolidation or other business combination
    involving Roberts or Shire, as the case may be, or the acquisition of all
    or any significant part of the assets or capital stock of Roberts or
    Shire, as the case may be; or

  . negotiate, explore or otherwise engage in discussions with any person
    with respect to any transaction referred to above, or which may
    reasonably be expected to lead to a proposal for such a transaction or
    enter into any agreement, arrangement or understanding with respect to
    any such transaction or which would require it to abandon, terminate or
    fail to consummate the merger or any other transaction contemplated by
    the merger agreement; provided, however, that Roberts and Shire may, in
    response to an unsolicited written proposal from a third party regarding
    a bona fide, written and unsolicited proposal or offer made by any
    persons or group with respect to a merger, consolidation or other
    business combination or an acquisition of all or any significant part of
    the assets or capital stock of Roberts or Shire, as the case may be, on
    terms which the board of directors of Roberts or Shire, as the case may
    be, determines in good faith, and in the exercise of reasonable judgment,
    based on the advice of independent financial advisors and legal counsel,
    to be more favorable to its shareholders than the merger, furnish
    information to, negotiate or otherwise engage in discussions with such
    third party, if the board of directors of Roberts or Shire, as the case
    may be, determines in good faith, after consultation with its financial
    advisors and based upon advice of outside counsel that such action is
    required for the board of directors to comply with its fiduciary duties
    under applicable law.

   According to the terms of the merger agreement, Roberts and Shire have
agreed to promptly advise each other of any information they have from a person
with respect to any transaction of the type referred to above and to give each
other an update on an ongoing basis or upon the reasonable request of Roberts
or Shire, as the case may be, on the status of any such transaction.

Conditions to Consummation of the Merger

 Conditions to Each Party's Obligations to Consummate the Merger

   The respective obligations of Roberts, Shire and Acquisition Sub to effect
the merger are subject to the satisfaction or waiver of the following
conditions:

  .  Shareholder Approvals. The merger and the other transactions
     contemplated by the merger agreement having been duly approved by the
     requisite vote of Roberts and Shire shareholders;

                                       70
<PAGE>

  .  Certain Approvals. All filings, notices, approvals, confirmations,
     consents, declarations and/or decisions required to be made, given or
     obtained by Roberts or Shire with or from any governmental or regulatory
     authority in connection with the consummation of the merger and the
     other transactions contemplated by the merger agreement;

  .  No Proceeding or Litigation. No order, injunction, decree or judgment of
     any court or governmental body or agency being in effect which
     materially restrains or prohibits the transactions contemplated by the
     merger agreement, and no suit, action, investigation, inquiry or
     proceeding by any governmental body or agency or legal or administrative
     proceeding by any governmental body or agency having been instituted, or
     threatened in writing, which questions the validity or legality of the
     transactions contemplated by the merger agreement;

  .  Securities Laws. The registration statements on Forms F-4 and F-6 having
     become effective and there not being any stop order or proceedings
     seeking a stop order with respect to such registration statements.

 Additional Conditions to the Obligations of Roberts

   The obligation of Roberts to effect the merger is subject to the
satisfaction or waiver of each of the following additional conditions prior to
the effective time:

  .  Representations and Warranties. Each of the representations and
     warranties of Shire and Acquisition Sub set forth in the merger
     agreement being true and correct in all material respects at and as of
     the effective time as if made at and as of such time and Roberts having
     received a certificate signed on behalf of Shire and Acquisition Sub to
     such effect, except that where any statement in a representation or
     warranty expressly includes a standard of materiality, such statement
     shall be true and correct in all respects giving effect to such
     standard;

  .  Agreements. Shire and Acquisition Sub having performed or complied in
     all material respects with each covenant, agreement and obligation to be
     performed or complied with by it under the merger agreement on or prior
     to the closing date, and Roberts having received a certificate signed on
     behalf of Shire and Acquisition Sub to such effect;

  .  Consents from Third Parties. Shire having obtained the consent or
     approval of each person whose consent or approval is required in order
     to consummate the merger and the other transactions contemplated by the
     merger agreement;

  .  Listing. The London Stock Exchange having granted admission of the
     ordinary shares comprising the merger consideration to the Official
     List, subject only to allotment; and the allotment of the ordinary
     shares comprising the merger consideration having occurred, subject only
     to admission becoming effective in accordance with paragraph 7.1 of the
     Listing Rules of the London Stock Exchange;

  .  Tax Opinions. Roberts having received an opinion dated on or about the
     date that is two business days prior to the date this Prospectus-Proxy
     Statement is first being mailed, relying on appropriate representations,
     of either Milbank, Tweed, Hadley & McCloy LLP, U.S. special counsel to
     Roberts, or Cahill Gordon & Reindel, U.S. counsel to Shire, to the
     effect that the merger will constitute a reorganization described in
     Section 368(a)(1)(A) of the Internal Revenue Code of 1986, and Section
     368(a)(2)(E) of the Code and no gain or loss will be recognized by
     Roberts or any of its shareholders except that (i) a shareholder who
     receives cash in lieu of fractional ordinary shares or ADSs will
     recognize capital gain or capital loss equal to the difference between
     the cash received and such shareholder's basis of the shares of Roberts
     common stock allocated to the fractional interest and (ii) any
     shareholder required to enter into a gain recognition agreement within
     the meaning of Treas. Reg. (S) 1.367(a)-3(c)(1)(iii)(B) must do so in
     order to avoid immediate gain recognition and may be required to
     recognize gain at the time and in the amount specified in the gain
     recognition agreement;

  .  Pooling Letter. Roberts having received a letter from its independent
     auditors, dated as of the closing date, setting forth the concurrence of
     Roberts' independent auditors with the conclusion of Roberts' management
     that it will be appropriate to account for the merger as a "pooling of
     interests" under U.S.

                                       71
<PAGE>

   GAAP, Accounting Principles Board Opinion No. 16 and all rules,
   regulations and policies of the SEC, if the merger is consummated in
   accordance with the merger agreement; and

  .  Nasdaq. The ADSs being issued in the merger having been approved for
     listing on the Nasdaq National Market System.

 Additional Conditions to the Obligations of Shire and Acquisition Sub

   The obligation of Shire and Acquisition Sub to effect the merger is subject
to the satisfaction or waiver of each of the following additional conditions
prior to the effective time:

  .  Agreements. Roberts having performed or complied in all material
     respects with each covenant, agreement and obligation to be performed or
     complied with by it under the merger agreement on or prior to the
     closing date, and Shire having received a certificate signed on behalf
     of Roberts to such effect;

  .  Representations and Warranties. Each of the representations and
     warranties of Roberts set forth in the merger agreement being true and
     correct in all material respects at and as of the effective time as if
     made at and as of such time, and Shire having received a certificate
     signed on behalf of Roberts by an executive officer of Roberts to such
     effect, except that where any statement in a representation or warranty
     expressly includes a standard of materiality, such statement shall be
     true and correct in all respects giving effect to such standard; and

  .  Pooling Letter. Shire having received a letter from its independent
     auditors, dated as of the closing date, setting forth the concurrence of
     Shire's independent auditors with the conclusion of Shire's management
     that it will be appropriate to account for the merger as a "pooling of
     interests" under U.S. GAAP, Accounting Principles Board Opinion No. 16
     and all rules, regulations and policies of the SEC, if the merger is
     consummated in accordance with the merger agreement.

Termination; Effect of Termination

   The merger agreement may be terminated:

  .  by mutual written consent of Shire and Roberts;

  .  by either Shire or Roberts upon written notice to the other party if:

   -- any governmental entity has issued an order, decree or ruling or taken
      any other action permanently enjoining, restraining or otherwise
      prohibiting the consummation of the merger and such order, decree or
      ruling or other action has become final and nonappealable; or

   -- the effective time has not occurred on or before December 31, 1999
      unless a later date is established by mutual written consent of Shire
      and Roberts or unless the failure to consummate the merger is the
      result of a breach of a covenant set forth in the merger agreement or
      a misrepresentation or breach of any warranty set forth in the merger
      agreement by the party seeking to terminate the merger agreement;

  .  by the board of directors of Shire or Roberts if:

   -- Shire shareholder approval has not been obtained upon a vote taken at
      Shire's shareholder meeting; or

   -- Roberts shareholder approval has not been obtained upon a vote taken
      at the special meeting,

   unless due to delay or default on the part of Roberts, in the case of the
   Shire shareholder approval, or due to delay or default on the part of
   Shire or Acquisition Sub, in the case of the Roberts shareholder
   approval;

  .  by the Shire board if:

   -- there has been a breach in any material respect of any representation,
      warranty, covenant or agreement on the part of Roberts set forth in
      the merger agreement which breach is not curable on

                                      72
<PAGE>

      or prior to December 31, 1999, except, where any statement in a
      representation or warranty includes a standard of materiality, if such
      statement is true and correct in all respects giving effect to such
      standard; or

   -- the Roberts board fails to recommend the approval of the merger
      agreement and the merger to Roberts shareholders; or

   -- the Roberts board withdraws or amends or modifies in a manner adverse
      to Shire its recommendation or approval of the merger agreement or the
      merger or fails to reconfirm such recommendation within five business
      days of a reasonable written request for such confirmation by Shire;

  .  by the Shire board if it reasonably determines that a proposal for an
     acquisition of Shire is more favorable to its shareholders than the
     merger; provided, however, that Shire may not terminate the merger
     agreement unless:

   -- five business days has elapsed after delivery to Roberts of a written
      notice of such determination by the Shire board and, during such five-
      business-day period, Shire has informed Roberts of the material terms
      and conditions and financing arrangements of such proposal for an
      acquisition of Shire and the identity of the person or group making
      such proposal; and

   -- at the end of such five business-day period, the Shire board continues
      reasonably to believe that such proposal is more favorable to its
      shareholders than the merger and promptly thereafter Shire enters into
      a definitive acquisition, merger or similar agreement to effect such
      transaction;

  .  by the Roberts board if:

   -- there is a breach in any material respect of any representation,
      warranty, covenant or agreement on the part of Shire or Acquisition
      Sub set forth in the merger agreement which breach is not curable on
      or prior to December 31, 1999, except, where any statement in a
      representation or warranty includes a standard of materiality, if the
      statement is true and correct in all respects giving effect to such
      standard;

   -- the Shire board fails to recommend the approval of the merger
      agreement and the merger to Shire's shareholders; or

   -- the Shire board withdraws or amends or modifies in a manner adverse to
      Roberts its recommendation or approval of the merger agreement or the
      merger or fails to reconfirm such recommendation within five business
      days of a reasonable written request for such confirmation by Roberts;
      or

  .  by the Roberts board if it reasonably determines that a proposal for an
     acquisition of Roberts is more favorable to its shareholders than the
     merger; provided, however, that Roberts may not terminate the merger
     agreement unless:

   -- five business days has elapsed after delivery to Shire of a written
      notice of such determination by the Roberts board and, during such
      five-business-day period, Roberts has informed Shire of the material
      terms and conditions and financing arrangements of such proposal for
      an acquisition of Roberts and the identity of the person or group
      making such proposal; and

   -- at the end of such five business day period the Roberts board
      continues reasonably to believe that such proposal is more favorable
      to its shareholders than the merger and promptly thereafter Roberts
      enters into a definitive acquisition, merger or similar agreement to
      effect such transaction.

 Termination Payments Payable by Roberts

   Under the merger agreement, if any of the following events occur, Roberts
has agreed to pay Shire a termination fee of $30 million:

  .  Shire terminates the merger agreement because the Roberts board fails to
     approve the merger agreement and the merger or withdraws or amends its
     recommendation or approval or fails to reconfirm such

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   recommendation within five business days of a reasonable written request
   for such confirmation by Shire;

  .  Roberts terminates the merger agreement because the Roberts board
     reasonably believes that a proposal for an acquisition of Roberts is
     more favorable to its shareholders than the merger; or

  .  Shire or Roberts terminates the merger agreement because the effective
     time has not occurred on or prior to December 31, 1999 or Roberts
     shareholder approval has not been obtained following the public
     announcement other than by Shire of a proposal for a transaction for the
     acquisition of Roberts and such termination was not solely the result of
     any action or inaction by Shire and, prior to or within six months after
     any such termination described in this clause, Roberts or any of its
     subsidiaries enters into a definitive agreement for, or consummates, a
     transaction for the acquisition of Roberts in which the merger
     consideration received by Roberts or its shareholders in that
     transaction is equal to or greater than the value of the merger
     consideration received in the Shire/Roberts merger.

 Termination Payments Payable by Shire

   Under the merger agreement, if any of the following events occur, Shire has
agreed to pay Roberts a termination fee of $30 million:

  .  Roberts terminates the merger agreement because the Shire board fails to
     approve the merger agreement and the merger or withdraws or amends its
     recommendation or approval or fails to reconfirm such recommendation
     within five business days of a reasonable written request for such
     confirmation by Roberts; or

  .  Shire terminates the merger agreement because the Shire board reasonably
     believes that a proposal for an acquisition of Shire is more favorable
     to its shareholders than the merger; or

  .  Shire or Roberts terminates the merger agreement because the effective
     time has not occurred on or prior to December 31, 1999 or Shire
     shareholder approval has not been obtained following the public
     announcement other than by Roberts of a proposal for a transaction for
     the acquisition of Shire and such termination was not solely the result
     of any action or inaction by Roberts, and, prior to or within six months
     after any termination described in this clause, Shire or any of its
     subsidiaries enters into a definitive agreement for, or consummates, a
     transaction for the acquisition of Shire.

Amendment

   The merger agreement may be amended by the parties thereto at any time
before or after any required approval of matters presented in connection with
the merger by the shareholders of Roberts or the shareholders of Shire;
provided, however, that, after any such approval, no amendment can be made that
by law requires further approval by such shareholders without the further
approval of such shareholders. The merger agreement may be amended by an
instrument in writing signed on behalf of each of the parties thereto prior to
the effective time with respect to any of the terms contained therein;
provided, however, that, after the merger agreement is adopted by the Roberts
shareholders, no amendment or modification can change the amount or form of the
consideration to be paid pursuant to the merger agreement.

Waivers

   At any time prior to the effective time, either Shire, Roberts or
Acquisition Sub may:

  .  extend the time for the performance of any of the obligations or other
     acts of any other party to the merger agreement;

  .  waive any inaccuracies in the representations and warranties contained
     in the merger agreement or in any document delivered pursuant to the
     merger agreement; or

  .  subject to the amendment provisions described above, waive compliance by
     any other party to the merger agreement with any of the provisions of
     any of the agreements or with any conditions to its own obligations.

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                           THE SHAREHOLDER AGREEMENT

Shire Shareholder Agreements

   At the same time of the execution of the merger agreement, Shire entered
into shareholder agreements with Yamanouchi Group Holdings Inc., the owner of
5,048,500 shares, or 15.8%, of Roberts common stock, and Dr. Robert A.
Vukovich, the owner of 1,733,671 shares, or 5.4%, of Roberts common stock.
Under the shareholder agreements, each of Yamanouchi and Vukovich has agreed to
vote their respective shares of common stock for the approval and adoption of
the merger agreement and any actions required to be approved by shareholders
related thereto and against any proposal or transaction which could prevent or
delay the consummation of the merger agreement, except in certain limited
circumstances. In addition, under the shareholder agreements, Shire has agreed
to register the ADSs to be received by Yamanouchi and Vukovich in the merger on
a registration statement on Form S-3 for an offering to be made on a continued
or delayed basis in the future pursuant to Rule 415 under the Securities Act of
1933. Also, Yamanouchi and Vukovich have agreed not to transfer their Roberts
shares except in the merger and not to sell the Shire ordinary shares or ADSs
they will receive in the merger until the combined company has published 30
days of financial results.

Roberts Shareholder Agreements

   At the same time of the execution of the merger agreement, Roberts entered
into shareholder agreements with four limited partnerships controlled by
HealthCare Ventures which collectively own 12,214,810 ordinary shares of Shire.
Dr. James Cavanaugh, Shire's non-executive chairman, is the president of the
management company of these limited partnerships. Under these shareholder
agreements, HealthCare Ventures has agreed to vote such ordinary shares for the
approval and adoption of the merger agreement and any actions required to be
approved by shareholders related thereto and against any proposal or
transaction which could reasonably prevent or delay the consummation of the
merger agreement.

                              THE OPTION AGREEMENT

General

   At the same time of the execution of the merger agreement and as an
inducement and condition to entering into the merger agreement, Roberts and
Shire entered into an option agreement. The following description sets forth
the material provisions of the option agreement but is qualified in its
entirety by reference to the option agreement, which is filed as an exhibit to
the registration statement on Form F-4 and incorporated herein by reference in
its entirety.

   Under the option agreement, Roberts granted Shire an unconditional
irrevocable option to purchase a number of shares representing up to 19.9% of
the issued and outstanding shares of common stock of Roberts at a price per
share in cash equal to $30.00.

   The option agreement provides that Shire may exercise the option on only one
occasion prior to termination of the option agreement, in whole or in part, by
delivering a written notice, upon the occurrence of any event that entitles
Shire to receive a payment of $30 million from Roberts payable according to the
terms of the merger agreement.

   To the extent the option has not been exercised, the option agreement will
terminate upon the earlier of the effective time or termination of the merger
agreement in accordance with its terms unless Shire is entitled to receive the
$30 million payment from Roberts, in which case the option agreement will
terminate one business day after Shire receives such payment or the $30 million
payment could no longer be payable based on the terms of the merger agreement.

   Arrangements such as the option agreement are customarily entered into in
connection with corporate mergers and acquisitions in an effort to increase the
likelihood that the transactions will be consummated in

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<PAGE>

accordance with their terms, and to compensate the grantee for the efforts
undertaken and the expenses, losses and opportunity costs incurred by it in
connection with the transactions if they are not consummated under certain
circumstances involving an acquisition or potential acquisition of the issuer
by a third party. The option agreement was entered into to accomplish these
objectives. The option agreement may have the effect of discouraging offers by
third parties to acquire Roberts prior to the effective time, even if such
persons were prepared to offer to pay consideration to Roberts shareholders
which has a higher current market price than the ordinary shares or the ADSs
to be received by Roberts shareholders pursuant to the merger agreement.

   The option agreement is not subject to the approval of Roberts
shareholders, and is effective whether or not Roberts shareholders approve the
merger agreement at the special meeting.

Notice of Exercise

   According to the terms of the option agreement, Shire may exercise the
option by sending Roberts a written notice specifying

  .the number of Roberts shares to be purchased; and

  .a date for the closing of such purchase.

   Based on the terms of the option agreement, the date specified by Shire for
exercising the option must be not less than two business days nor more than
ten days from the later of (x) the date the exercise notice is given and (y)
the expiration or termination of any waiting period, and any extensions
thereof, under the Hart-Scott-Rodino Act.

Limitation on Total Profit

   The option agreement provides that in no event will the amount Shire
receives from the sum of the following exceed $32 million:

  . the amount before taxes but net of reasonable and customary commissions
    payable in connection with such transactions received by Shire from the
    sale of the shares of Roberts common stock acquired from exercise of the
    option less the exercise price for such Roberts shares;

  . any amounts before taxes but net of reasonable and customary commissions
    payable in connection with such transactions received by Shire on the
    transfer of the option to any unaffiliated persons or to Roberts; and

  . a $30 million payment by Roberts to Shire according to the terms of the
    merger agreement.

   If Shire would otherwise receive more than $32 million, Shire in its sole
discretion, will take one of the following actions to reduce this amount to
$32 million:

  .reduce the number of shares of Roberts common stock subject to the option;

  .pay cash to Roberts;

  .reduce the amount of the $30 million payment; or

  .any combination thereof.

   The option agreement also provides that the option may not be exercised for
a number of shares of Roberts common stock as would, as of the date notice is
given by Shire that it will exercise the option, result in the receipt by
Shire of a hypothetical amount of more than $32 million. For purposes of the
option agreement, this hypothetical amount is the sum of:

  . the amount before taxes but net of reasonable and customary commissions
    payable in connection with
   such transactions received by Shire from the sale of the shares of Roberts
   common stock acquired from exercise of the option less the exercise price
   for such Roberts shares;

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<PAGE>

  . any amounts before taxes but net of reasonable and customary commissions
    payable in connection with such transactions received by Shire on the
    transfer of the option to any unaffiliated persons or to Roberts; and

  . a $30 million payment by Roberts to Shire according to the terms of the
    merger agreement.

   This hypothetical amount is determined as of the date notice is given by
Shire that it will exercise the option, assuming that the option were exercised
on such date for the number of shares of Roberts common stock for which Shire
exercises the option and assuming that such shares were sold for cash at the
closing market price as of the close of business on the preceding trading day,
less customary brokerage commissions.

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<PAGE>

                           MATERIAL TAX CONSEQUENCES

General

   The following general discussion summarizes (i) the material U.S. federal
income tax consequences to U.S. persons who are deemed to be the beneficial
owners of shares of Roberts common stock who exchange their stock for ADSs or
ordinary shares in accordance with the merger and (ii) the material U.S. and
U.K. tax consequences to those persons of the ownership and disposition of ADSs
and ordinary shares. This discussion is based upon existing U.S. federal income
tax law and existing U.K. tax law, including legislation, regulations,
administrative rulings and court decisions, as in effect on the date hereof,
all of which are subject to change, possibly with retroactive effect. For U.S.
federal income tax purposes, a U.S. person is:

  .an individual citizen or resident of the U.S.;

  . a corporation created or organized in or under the laws of the U.S., any
    state thereof or the District of Columbia;

  . a partnership, trust or estate treated, for U.S. federal income tax
    purposes, as a domestic partnership, trust or estate.

   This discussion assumes that U.S. persons who are deemed to beneficially own
shares of Roberts common stock do so as a capital asset as of the effective
time. This discussion does not purport to address all material tax consequences
of ownership of ADSs or ordinary shares and does not discuss all aspects of
U.S. federal income taxation or U.K. taxation that may be relevant to all U.S.
persons who are deemed to beneficially own shares of Roberts common stock in
light of their particular circumstances, such as those whose stock was acquired
pursuant to the exercise of an employee stock option or otherwise as
compensation or U.S. persons who are subject to special treatment under the
U.S. federal income tax laws. This category includes those holders that hold
their stock as part of a straddle, hedge or conversion transaction, financial
institutions, insurance companies, tax-exempt organizations and broker-dealers.
This discussion of the income tax consequences also does not address any
aspects of state or local taxation or foreign taxation, other than certain U.K.
tax consequences. In general, for U.S. tax purposes, U.S. persons who are
deemed to be the beneficial owners of ADSs will be treated as the owners of the
underlying ordinary shares that are represented by such ADSs and deposits and
withdrawals of ordinary shares by those persons in exchange for ADSs will not
be subject to U.S. federal income tax. U.S. persons are urged to consult their
tax advisors regarding the U.S. federal, state and local and other tax
consequences of owning and disposing of ordinary shares and ADSs. In
particular, U.S. persons are urged to confirm with their advisors that they are
beneficial owners of ordinary shares or ADSs and of the cash dividend paid with
respect thereto and that they:

  . are an individual or a corporation resident in the U.S. for purposes of
    the United Kingdom-United States Income Tax Convention (and, in the case
    of a corporation are not also resident in the U.K. for U.K. tax
    purposes);

  . are not a corporation which, alone or together with one or more
    associated corporations, controls, directly or indirectly, 10% or more of
    the voting stock of Shire;

  . hold the ordinary shares or ADSs in a manner which is not effectively
    connected with a permanent establishment in the U.K. through which such
    U.S. person carries on business or with a fixed base in the U.K. from
    which such person performs independent personal services; and

  . are not otherwise ineligible for benefits under the U.K.-U.S. Income Tax
    Convention with respect to income and gains derived in connection with
    the ordinary shares or ADSs.

The U.S. and the U.K. have announced that they intend to enter into
negotiations to update the U.K.-U.S. Income Tax Convention.

   U.S. persons are also urged to discuss with their advisors any possible
consequences of their failure to meet the qualifications of the immediately
preceding paragraph.

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<PAGE>

   Each U.S. person deemed to beneficially own shares of Roberts common stock
is advised to consult his, her or its own tax advisors as to the U.S. federal
income tax and U.K. tax consequences of the merger including the facts and
circumstances that may be unique to that person, and as to any estate, gift,
state, local or non-U.S. tax consequences of the merger and the ownership and
disposition of ADSs or ordinary shares.

United States Tax Consequences of the Merger to U.S. Persons That Beneficially
Own Shares of Roberts Common Stock

   The merger is intended to qualify as a reorganization within the meaning of
Section 368(a) of the Code. The obligation of Roberts to consummate the merger
is conditioned upon the receipt by Roberts of a tax opinion, based on
appropriate representations, of either Milbank, Tweed, Hadley & McCloy LLP or
Cahill Gordon & Reindel, to the effect that for U.S. federal income tax
purposes (i) the merger will be treated as a reorganization within the meaning
of Section 368(a) of the Code; and (ii) no gain or loss will be recognized by a
U.S. shareholder of Roberts common stock on the exchange of shares of Roberts
common stock for ADSs or ordinary shares, except with respect to cash received
in lieu of a fractional interest in an ADS or an ordinary share. See "The
Merger Agreement--Conditions to Consummation of the Merger." This tax opinion
will be expressly based upon the accuracy of certain representations made to
such counsel by Roberts and Shire, as well as upon certain assumptions. The
assumptions made may include the assumption that a U.S. person that is a "5%
shareholder" of Shire after the merger will, in accordance with applicable
Treasury Regulations under Section 367(a) of the Code, file a gain recognition
agreement with the IRS, as explained more fully below. For purposes of this
discussion, whether a U.S. person is a "5% shareholder" of Shire after the
merger will be determined in accordance with applicable Treasury Regulations
under Section 367(a) of the Code.

   Roberts is permitted under the merger agreement to waive the receipt of the
tax opinion as a condition to its obligation to consummate the merger, although
it does not intend to do so. Roberts will not waive the condition without first
recirculating revised proxy materials and resoliciting the vote of Roberts
shareholders. Furthermore, this tax opinion is not binding on the IRS or a
court and does not preclude the IRS or a court from adopting a contrary
position. Roberts will not seek a ruling from the IRS as to the tax treatment
of the merger as a reorganization or as a non-recognition exchange of shares of
Roberts common stock for ordinary shares or ADSs.

   Fractional interests in ADSs or ordinary shares will not be issued to
Roberts shareholders in the merger. Instead, Roberts shareholders will receive
cash for any fractional ADS or fractional ordinary share owed to them based
upon the trading prices of these securities on the trading day immediately
following the merger. A U.S. person who receives cash with respect to the sale
of a fractional ADS or ordinary share will be treated as having received a
fractional ADS or ordinary share pursuant to the merger and then as having sold
that fractional ADS or ordinary share for cash. The amount of any capital gain
or loss attributable to that sale will be equal to the difference between the
cash received with respect to the fractional ADS or ordinary share and the tax
basis that is allocated to the fractional ADS or ordinary share. In the case of
an individual U.S. person, any gain will be subject to U.S. federal income tax
at a maximum rate of 20% if the U.S. person has a holding period for the
fractional ADS or ordinary share of more than 12 months at the effective time.
This holding period will include the U.S. person's holding period for the
Roberts common stock deemed exchanged for the fractional ADS or ordinary share.

   A U.S. person deemed to beneficially own shares of Roberts common stock who:

  .receives ADSs or ordinary shares in the merger;

  .is a "5% shareholder" of Shire after the merger; and

  . fails to file an agreement with the IRS as provided by Treasury
    Regulations Section 1.367(a)-8 which generally allows a U.S. person to
    avoid recognizing gain at the time of a transfer of domestic stock to a
    foreign corporation;

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will not qualify for non-recognition treatment and will recognize any gain but
not any loss. In the case of an individual U.S. person deemed to beneficially
own shares of Roberts common stock, any gain would be subject to U.S. federal
income tax at a maximum rate of 20% if that person has a holding period in its
shares of Roberts common stock of more than 12 months at the effective time.
Any holder of shares of Roberts common stock who will be a "5% shareholder" of
Shire after the merger is urged to consult with his, her or its own tax advisor
concerning the decision to file such an agreement with the IRS and the
procedures to be followed in connection with that filing.

United States Tax Consequences of the Ownership of Ordinary Shares and ADSs to
U.S. Persons that Beneficially Own Shares of Roberts Common Stock

   The following is a summary of material U.S. federal income tax consequences
of the ownership of ordinary shares or ADSs by a U.S. person that receives ADSs
or ordinary shares in connection with the merger and holds ordinary shares or
ADSs as capital assets.

 Taxation of Dividends

   Under the U.S. federal income tax laws, U.S. persons will include in gross
income the gross amount of any dividend paid by Shire out of its current or
accumulated earnings and profits, as determined for U.S. federal income tax
purposes, as ordinary income when the dividend is actually or constructively
received by such person, in the case of ordinary shares, or by the depositary,
in the case of ADSs. The dividend will not be eligible for the dividends-
received deduction generally allowed to U.S. corporations in respect of
dividends received from other U.S. corporations. Distributions in excess of
current and accumulated earnings and profits, as determined for U.S. federal
income tax purposes, will be treated as a return of capital to the extent of
the U.S. person's basis in the ordinary shares or ADSs and thereafter as
capital gain. As a result of recent changes in U.K. law, the payment from the
U.K. Inland Revenue that certain U.S. persons would otherwise be entitled to
receive under the U.K.-U.S. Income Tax Convention in connection with a dividend
paid by Shire is now completely offset by a corresponding U.K. withholding tax.
See "--United Kingdom Tax Consequences of the Ownership of Ordinary Shares and
ADSs to U.S. Persons That Beneficially Own Shares of Roberts Common Stock--
Taxation of Distributions." Even though no net payment under the treaty is
made, a U.S. person receiving a dividend from Shire generally will be required
to include in income the gross amount of the treaty payment as a dividend and
be entitled to a foreign tax credit or deduction in respect of the withholding
tax, as discussed below.

   Subject to certain limitations and the provisions of the next paragraph, any
U.K. withholding tax will be creditable against the U.S. person's U.S. federal
income tax liability. See "--United Kingdom Tax Consequences of the Ownership
of Ordinary Shares and ADSs to U.S. Persons That Beneficially Own Shares of
Roberts Common Stock." For foreign tax credit limitation purposes, the dividend
will be income from sources outside the U.S., but generally will be treated
separately, together with other items of "passive income," or, in the case of
certain holders, "financial services income." The rules relating to the
determination of the foreign tax credit are complex and U.S. persons deemed to
beneficially own shares of Roberts common stock should consult with their own
tax advisors to determine whether and to what extent a credit would be
available. U.S. persons that do not elect to claim a foreign tax credit may
instead claim a deduction for any U.K. withholding tax.

   It is anticipated that, after the merger, Shire will be at least 50% owned
by U.S. persons. Under Section 904(g) of the Code, dividends paid by a foreign
corporation that is at least 50% owned by U.S. persons may be treated as U.S.
source income rather than foreign source income for foreign tax credit purposes
to the extent the foreign corporation has more than an insignificant amount of
U.S. source income, and the effect of this rule may be to treat a portion of
the dividends paid by Shire as U.S. source income. Section 904(g)(10) of the
Code permits a U.S. person to elect to treat Shire dividends as foreign source
income for foreign tax credit limitation purposes, if the dividend income is
separated from other income items for purposes of calculating the holder's
foreign tax credit. Although there is no form prescribed for making this
election, applicable Treasury Regulations suggest that the election is made by
claiming the credit in the manner described in this paragraph.

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 Taxation of Capital Gains

   Upon a sale or other disposition of ordinary shares or ADSs, a U.S. person
will recognize gain or loss for U.S. federal income tax purposes in an amount
equal to the difference between the U.S. dollar value of the amount realized
and the U.S. person's tax basis in such ordinary shares or the ADSs. The
determination of the U.S. person's tax basis is made in U.S. dollars.
Generally, gain or loss will be long-term capital gain or loss if the U.S.
person's holding period for the ordinary shares or ADSs exceeds one year and
any such gain generally will be income from sources within the U.S. for foreign
tax credit limitation purposes. Any loss realized by a U.S. person generally
will be treated as from sources within or without the U.S. for purposes of the
foreign tax credit. Long-term capital gain for a non-corporate U.S. person is
generally subject to a maximum tax rate of 20%.

 Backup Withholding and Information Reporting

   In general, information reporting requirements will apply to dividend
payments or other taxable distributions in respect of ordinary shares or ADSs
made within the U.S. to a non-corporate U.S. person, and "backup withholding"
at the rate of 31% will apply to the payments if the holder or beneficial owner
fails to provide an accurate taxpayer identification number in the manner
required by U.S. law and applicable regulations, if there has been notification
from the IRS of a failure by the holder or beneficial owner to report all
interest or dividends required to be shown on its federal income tax returns
or, in certain circumstances, if the holder or beneficial owner fails to comply
with applicable certification requirements.

   In general, payment of the proceeds from the sale of ordinary shares or ADSs
to or through a U.S. office of a broker is subject to both U.S. backup
withholding and information reporting requirements, unless the holder or
beneficial owner certifies its non-U.S. status under penalties of perjury or
otherwise establishes an exemption. U.S. information reporting and backup
withholding generally will not apply to a payment made outside the U.S. of the
proceeds of a sale of ordinary shares or ADSs through an office outside the
U.S. of a non-U.S. broker. However, U.S. information reporting requirements but
not backup withholding will apply to a payment made outside the U.S. of the
proceeds of a sale of ordinary shares or ADSs through an office outside the
U.S. of a broker:

  .that is a U.S. person;

  . that derives 50% or more of its gross income for a specified three-year
    period from the conduct of a trade or business in the U.S.;

  .that is a "controlled foreign corporation" as to the U.S.; or

  . with respect to payments made after December 31, 2000, that is a foreign
    partnership, if at any time during its tax year, one or more of its
    partners are U.S. persons (as defined in U.S. Treasury Regulations) who
    in the aggregate hold more than 50% of the income or capital interest in
    the partnership or if, at any time during its tax year, such foreign
    partnership is engaged in a U.S. trade or business, unless the broker has
    documentary evidence in its files that the holder or beneficial owner is
    a non-U.S. person or the holder or beneficial owner otherwise establishes
    an exemption.

   Amounts withheld under the backup withholding rules may be credited against
a U.S. person's U.S. tax liability, and a holder may obtain a refund of any
excess amounts withheld under the backup withholding rules by filing the
appropriate claim for refund with the IRS.

United Kingdom Tax Consequences of the Ownership of Ordinary Shares and ADSs to
U.S. Persons That Beneficially Own Shares of Roberts Common Stock

   The tax treatment of dividends paid in respect of the ordinary shares and
ADSs will depend upon the U.K. law and practice in force at the time dividends
are paid. The following summary is based upon U.K. law and practice, including
the U.K.-U.S. Income Tax Convention and the United Kingdom-United States Estate
and Gift Tax Convention, which may change. The summary of U.K. tax matters
below does not address the tax

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consequences for U.S. Persons that are resident (or, in the case of
individuals, ordinarily resident) in the U.K. for U.K. tax purposes or for the
purposes of the Treaty or that are corporations which, alone or together with
one or more associated companies, control directly or indirectly 10% or more of
the voting stock or power of Shire. For the purposes of the U.K.-U.S. Income
Tax Convention, U.S. persons who are deemed to beneficially own ADSs will be
treated as owners of the ordinary shares underlying the ADSs.

 Taxation of Distributions

   Dividends paid by Shire to U.S. persons generally will not be subject to any
U.K. withholding tax.

   Under the U.K.-U.S. Income Tax Convention, certain U.S. persons that receive
a dividend from Shire are entitled to a payment form the U.K. Inland Revenue in
an amount equal to the tax credit to which a U.K. resident individual taxpayer
would have been entitled had he received the dividend. This payment from the
U.K. Inland Revenue generally is subject to a U.K. withholding tax equal to 15%
of the sum of the cash dividend and the tax credit to which a U.K. resident
individual would have been entitled, up to a maximum of the amount of the tax
credit. As a result of a recent change in U.K. law, the amount of the tax
credit has been reduced to an amount lower that the 15% U.K. withholding tax.
Accordingly, no U.S. person will be entitled to receive any net payment from
the U.K. Inland Revenue under the U.K.-U.S. Income Tax Convention.

   For example, if Shire were to pay a cash dividend of $90, certain U.S.
persons entitled to the benefits of the U.K.-U.S. Income Tax Convention would
be entitled to receive a payment from the U.K. Inland Revenue of $10 minus U.K.
withholding tax. The amount of U.K. withholding tax would be $10, which is the
lesser of $10 and 15% of the sum of the base dividend of $90 and the $10
payment. As a result, the U.S. persons would receive the $90 dividend from
Shire but no net payment from the U.K. Inland Revenue. Although no net payment
is received from the U.K. Inland Revenue, the gross amount of the $10 tax
credit and the related $10 U.K. withholding tax generally must be taken into
account separately for United States federal income tax purposes, as discussed
above. See "United States Tax Consequences of the Ownership of Ordinary Shares
and ADSs to U.S. Persons That Beneficially Own Shares of Roberts Common Stock--
Taxation of Dividends."

 Taxation of Capital Gains

   A U.S. person who is not resident or ordinarily resident for tax purposes in
the U.K. normally will not be liable for U.K. tax on capital gains realized on
the disposal of his ordinary shares or ADSs unless at the time of the disposal,
the U.S. person carries on a trade, which for this purpose includes a
profession or vocation, in the U.K. through a branch or agency and the ordinary
shares or ADSs are or have been used, held or acquired for the purposes of that
trade or branch or agency. A U.S. person who is an individual and who has, on
or after March 17, 1998, ceased to be resident or ordinarily resident for tax
purposes in the U.K. for a period of less than five tax years and who disposes
of ordinary shares or ADSs during that period may be liable for U.K. tax on
capital gains realized, subject to any available exemption or relief.

 Inheritance and Gift Taxes

   Provided that any gift or estate tax due in the U.S. is paid, the U.K.-U.S.
Estate and Gift Tax Convention generally relieves from U.K. inheritance tax the
transfer of ordinary shares or of ADSs where the shareholder or holder of the
ordinary shares or ADSs making the transfer is domiciled, for the purposes of
the U.K.-U.S. Estate and Gift Tax Convention, in the U.S. and not a national of
the U.K. for the purposes of the U.K.-U.S. Estate and Gift Tax Convention. This
will not apply if the ordinary shares or ADSs are part of the business property
of an individual's permanent establishment of an enterprise in the U.K. or
pertain to the fixed base in the U.K. of a person providing independent
personal services. In the unusual case where ordinary shares or ADSs are
subject to both U.K. inheritance tax and U.S. estate or gift tax, the U.K.-U.S.
Estate and Gift Tax Convention generally provides for tax paid in the U.K. to
be credited against tax payable in the U.S. or for tax paid in the U.S. to be
credited against tax payable in the U.K. based on priority rules set forth in
the U.K.-U.S. Estate and Gift Tax Convention.

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 Stamp Duty and Stamp Duty Reserve Tax

   Shire and Roberts will be jointly and severally liable for all stamp duties,
stamp duty reserve tax and other similar taxes and governmental levies imposed
in connection with the issuance or creation of the ordinary shares constituting
the merger consideration and any ADSs in connection therewith and any other
U.K. stamp duty, stamp duty reserve tax, other similar governmental charge or
any interest or penalties thereon that may be payable by Shire and Roberts
pursuant to the Deposit Agreement. See "Description of American Depositary
Shares and American Depositary Receipts."

   Any tax or duty payable by the Depositary or the Custodian on the initial
issue of ADSs to the Depositary or the Custodian as the provider of clearance
services or the issuer of depositary receipts will be charged by the Depositary
or the Custodian to Shire and Roberts.

   If ADSs are transferred after initial issue into a clearance service or
depositary receipt arrangement, including a transfer of ADSs to the Custodian,
stamp duty and/or stamp duty reserve tax will be payable in respect of the
ADSs. The stamp duty and/or stamp duty reserve tax is generally payable on the
consideration given for the transfer and is payable at the rate of, 1.5 percent
rounded up if necessary to the nearest multiple of (Pounds)5 in the case of
stamp duty or 1.5 percent in the case of stamp duty reserve tax.

   In accordance with the terms of the Deposit Agreement, any tax or duty
payable by the Depositary or the Custodian on any transfer of ADSs to the
Depositary or the Custodian after the initial issue of ADSs will be due and
payable by the holder of the resulting ADSs to the Depositary. See "Description
of American Depositary Shares and American Depositary Receipts."

   No stamp duty will be payable on the acquisition or transfer of ADRs
representing ADSs or beneficial ownership of ADRs representing ADSs, provided
that any instrument of transfer or written agreement to transfer remains at all
times outside the U.K. and provided further that any instrument of transfer or
written agreement to transfer is not executed in the U.K. and the transfer does
not relate to any matter or thing done or to be done in the U.K. An agreement
for the transfer of ADRs representing ADSs or beneficial ownership of ADRs
representing ADSs will not give rise to a liability for stamp duty reserve tax.

   A transfer for value of the ordinary shares generally will be subject to ad
valorem stamp duty, and potentially also to stamp duty reserve tax. Stamp duty
will arise on the execution of an instrument to transfer ordinary shares and
stamp duty reserve tax will arise on the entry into an agreement, in writing or
otherwise, to sell ordinary shares. If a stock transfer form is executed and
duly stamped within six years of the entering into of an agreement to transfer
U.K. shares, any outstanding stamp duty reserve tax liability will be cancelled
and any stamp duty reserve tax which has been paid may be reclaimed. Stamp duty
and stamp duty reserve tax are normally a liability of the transferee. Any
transfer for value of the underlying ordinary shares represented by ADSs may
give rise to a liability on the transferee to U.K. stamp duty or stamp duty
reserve tax. The amount of stamp duty is calculated at the applicable rate on
the consideration for the transfer of the ordinary shares, this being 1.5
percent rounded up if necessary to the nearest multiple of (Pounds)5 and 1.5
percent of the amount or value of the consideration in the case of stamp duty
reserve tax. On a transfer of ordinary shares from the custodian of the
depositary to a holder of an ADS upon cancellation of the ADS, only fixed stamp
duty per instrument of transfer will be payable, which is currently (Pounds)5
per instrument.


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                       DESCRIPTION OF SHIRE SHARE CAPITAL

   The following sections include information concerning the ordinary shares,
based on English law and a summary of material provisions of the Memorandum and
Articles of Association of Shire. This information and summary do not purport
to be complete and are qualified in their entirety by reference to the full
Memorandum and Articles of Association, copies of which have been filed as
exhibits to the registration statement of which this Prospectus-Proxy Statement
forms a part.

General

   All of Shire's issued ordinary shares are, and all of the ordinary shares
issued pursuant to the merger in the form of ADSs represented by ADRs will be,
upon completion of the offering, fully paid or credited as fully paid and
nonassessable. Certificates representing the ordinary shares are issued in
registered form, although a directors' resolution passed on September 26, 1996
authorized the transfer of shares in Shire by means of CREST, a paperless
settlement system enabling securities to be evidenced otherwise than by a
certificate and transferred otherwise than by a written instrument. So long as
this directors' resolution is in force, the Articles of Association in relation
to the ordinary shares will not apply to any uncertificated ordinary shares to
the extent that the Articles of Association are inconsistent with the holding
of ordinary shares in uncertificated form, the transfer of title to any
ordinary shares by means of the CREST system and any provisions of the
regulations relating to CREST. Under English law, shareholders who are not
residents of the U.K. may hold, vote and transfer their shares in the same
manner as U.K. residents but the Articles provide that, where a shareholder has
a registered address outside the U.K., the shareholder is not entitled to
receive any notice from Shire unless that shareholder has specified an address
within the U.K. at which these notices may be served.

Share Capital

   Shire was incorporated with an authorized share capital of (Pounds)50,000
divided into 50,000 ordinary shares of (Pounds)1 each, of which two shares were
taken by the subscribers to the Memorandum of Association.

   The authorized share capital of Shire at the date of this Prospectus-Proxy
Statement is, and immediately prior to the effective time will be,
(Pounds)10,000,000 divided into 200,000,000 ordinary shares, of which
[141,092,000] ordinary shares of 5p each are in issue at the date of this
Prospectus-Proxy Statement. An aggregate of [ ] ordinary shares of 5p each will
be issued upon completion of the merger.

   By ordinary resolution passed on May 10, 1999, the directors were generally
and unconditionally authorized to exercise all powers of Shire to allot
relevant securities, within the meaning of Section 80 of the Companies Act, up
to an aggregate nominal amount of (Pounds)2,361,070. This authority expires on
the earlier of fifteen months after the date of this resolution and the
conclusion of the annual general meeting of Shire in 2000. However, Shire may
make offers or agreements before the expiration which would or might require
relevant securities to be allotted after the expiration and the directors may
allot relevant securities in pursuance of the offers or agreements as if the
authority conferred by that resolution had not expired.

   By special resolution passed on May 10, 1999, the directors were empowered
under Section 95(1) of the Companies Act to allot equity securities, as defined
in Section 94(2) of the Companies Act, under the authority referred to in the
paragraph above as if Section 89(1) of the Companies Act relating to
shareholders' rights of pre-emption did not apply to any of these allotments,
provided that this power is limited to:

  . the allotment of equity securities in connection with a rights issue,
    open offer or otherwise in favor of ordinary shareholders where the
    equity securities have been offered to holders of ordinary shares as
    nearly in proportion to their then holdings of ordinary shares, provided
    that the directors may make such exclusion or other arrangements as they
    may deem necessary or expedient to deal with fractional entitlements,
    ordinary shares represented by depositary receipts or legal or practical
    problems under the laws of, or the requirements of, any recognized
    regulatory body or stock exchange in any territory; and

  . the allotment of equity securities for cash up to an aggregate nominal
    amount of (Pounds)354,515 otherwise than pursuant to the previous
    paragraph.


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<PAGE>

   This power expires on the earlier of fifteen months from the date of the
resolution or the conclusion of the annual general meeting of Shire in 2000,
except that Shire may before this expiration make an offer or agreement that
would or might require equity securities to be allotted after the expiration
and the directors may allot equity securities under the offer or agreement as
if that power had not expired.

   The provisions of Section 89(1) of the Companies Act confer on shareholders
rights of pre-emption in respect of the allotment of equity securities which
are, or are to be, paid in cash, other than by way of allotment to employees
under an employees' share scheme as defined in Section 743 of the Companies
Act. This section applies to the authorized but unissued share capital of
Shire, to the extent not disapplied in accordance with Section 95 of the
Companies Act.

Dividends

   Subject to the Companies Act and other applicable law, Shire may by ordinary
resolution from time to time declare dividends to be paid to shareholders
according to their rights and interests in the profits available for
distribution, but no dividend shall be declared in excess of the amount
recommended by the board of directors. Except insofar as the rights attaching
to, or the terms of issue of, any share in Shire otherwise provide, all
dividends shall be apportioned and paid proportionately according to the
amounts paid on the shares during any portion or portions of the period in
respect of which the dividend is paid. The board of directors may from time to
time and subject to the Companies Act and other applicable law also pay to the
shareholders an amount of interim dividends that the board of directors
considers to be justified by the profits of Shire available for distribution.
The board may, if authorized by an ordinary resolution of Shire, allot to those
holders of a particular class of shares who have elected to receive them
further shares of that class or ordinary shares instead of cash in respect of
all or part of a dividend or dividends specified by the resolution. The value
of the shares allotted will be calculated by reference to the average of the
middle market quotations for a fully-paid share of Shire of that class derived
from the Daily Official List of the London Stock Exchange for the five business
days commencing on the day the ordinary shares are first quoted "ex" the
relevant dividend. Final dividends are recommended by the board of directors
following the end of the fiscal year to which they relate and are paid subject
to approval by the shareholders at Shire's annual general meeting pursuant to
an ordinary resolution. Any dividend unclaimed for a period of 12 years from
the date such dividend is due for payment shall be forfeited and shall cease to
remain owing by Shire.

   Where a person is, under the provisions as to the transmission of shares
contained in the Articles of Association, entitled to become a shareholder, the
board may at any time serve a notice on this person requiring him to elect
either to be registered himself or to have a person nominated by him registered
as a member. If the notice is not complied with within 60 days, the board may
withhold payment of all dividends payable in respect of these shares until the
requirements of the notice have been complied with. Where any person has an
interest of 0.25% or more in the nominal value of shares of a particular class
in Shire, the board may withhold dividends payable on shares held by this
person if there has been a failure to provide Shire with information concerning
interests on those shares required to be provided under the Articles of
Association and the Companies Act until this failure has been remedied.

Rights in a Winding-Up

   Holders of ordinary shares are entitled to participate in any distribution
of the balance of the assets on a winding-up, after provision for or payment of
liabilities and creditors under the Insolvency Act 1986 and the Companies Act.
On a winding-up, the liquidator may, with any sanction required by law divide
among the shareholders the whole or any part of the assets of Shire in kind,
whether they shall consist of property of the same kind or not, and, for that
purpose, set those values as the liquidator determines fair upon any property
to be divided and determine how the division shall be carried out as between
the shareholders or different classes of shareholders.

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<PAGE>

Shareholder Meetings

   An annual general meeting of shareholders must be held once each year within
a period of not more than 15 months after the date of the last preceding annual
general meeting. The board of directors may convene an extraordinary general
meeting of shareholders at its discretion. General meetings may be held at the
time and place as may be determined by the board of directors. An annual
general meeting shall be convened on at least 21 days' written notice to
shareholders entitled to receive notices. Most extraordinary general meetings
may be convened on at least 14 days' written notice, but extraordinary general
meetings at which it is proposed to pass special resolutions must be convened
on at least 21 days' written notice. Two shareholders entitled to vote must be
present in person or by proxy to constitute a quorum for all purposes at
general meetings except that the absence of a quorum shall not preclude the
choice or appointment of a chairman of the meeting.

Voting Rights

   Subject to any special rights, terms or restrictions as to voting upon which
any shares may be issued or held and to any other provisions of the Articles of
Association, every shareholder present in person at a general meeting shall
have one vote on a show of hands, and on a poll every shareholder present in
person or by proxy shall have one vote for every ordinary share of which he is
the holder. No shareholder shall, unless otherwise authorized by the board of
directors, be entitled to be present or vote at any general meeting of Shire or
at any separate general meeting of the holders of any class of shares in Shire
unless all calls or other sums presently payable by the shareholder in respect
of shares in Shire have been paid. See also "--Disclosure of Interests" below.
For a description of the method by which the ordinary shares held by the
Depositary will be voted, see "Description of American Depositary Shares and
American Depositary Receipts --Voting Rights."

   Voting at any general meeting of shareholders is by a show of hands unless a
poll is duly demanded. A poll may be demanded by:

  .the chairman of the meeting;

  .not less than five shareholders present in person or by proxy entitled to
     vote at the meeting;

  . any shareholder or shareholders present in person or by proxy and
    representing in aggregate not less than one-tenth of the total voting
    rights of all shareholders entitled to attend and vote at the meeting; or

  . any shareholder or shareholders present in person or by proxy holding
    shares conferring a right to attend and vote at the meeting on which
    shares there have been paid sums in the aggregate equal to not less than
    one-tenth of the total sum paid on all the shares conferring that right.

   Since under English law voting rights are only conferred on registered
holders of shares, a person holding through a nominee may not directly demand a
poll. This includes holders of ADSs that are not registered holders of shares.

   Unless otherwise required by law or the Articles of Association, voting in a
general meeting is by ordinary resolution. This category includes:

  .resolutions for the election of directors;

  .the approval of financial statements;

  .the declaration of final dividends;

  .the appointment of auditors;

  .the increase of authorized share capital; and

  .the grant of authority to issue shares.

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<PAGE>

   An ordinary resolution requires the affirmative vote of a majority of the
votes of those who are eligible to vote and vote in person in the case of
individuals or are represented by duly authorized representatives in the case
of corporations. If a poll is demanded, the affirmative vote of shareholders
who are present in person or by proxy in the case of individuals or are
represented by duly authorized representatives in the case of corporations and
who in the aggregate hold shares conferring a majority of the votes actually
cast on the resolution is required. A special resolution or an extraordinary
resolution requires the affirmative vote of not less than three-fourths of
those who are eligible to vote and vote in person in the case of individuals or
are represented by duly authorized representatives in the case of corporations.
If a poll is demanded, the affirmative vote of shareholders who are present in
person or by proxy in the case of individuals or are represented by duly
authorized representatives in the case of corporations and who in the aggregate
hold shares conferring three-fourths of the votes actually cast on the
resolution is required. Examples of special resolutions include resolutions
relating to matters concerning an alteration of Shire's Memorandum of
Association or Articles of Association or a members' voluntary winding-up of
Shire or the disapplication of statutory preemption rights in respect of the
issuance of equity securities to be paid wholly in cash. An example of an
extraordinary resolution is one which modifies the rights of any class of
shares at a meeting of the holders of such class. The chairman of the meeting
has a second or deciding vote in the case of a tied vote.

Authorization to Issue Shares; Preemptive Rights

   The Companies Act provides that the directors may be authorized by means of
an ordinary resolution of the shareholders to issue up to the maximum number of
ordinary shares designated in such resolution for a maximum period not
exceeding five years, although generally in the case of companies whose shares
are quoted on the Official List of the London Stock Exchange, these
authorizations expire and are renewed at the same time as the disapplication of
pre-emptive rights. See "--Share Capital" above. The Companies Act confers on
shareholders, to the extent not disapplied and other than in respect of
issuances under employee share plans, rights of pre-emption in respect of the
issuance of equity securities that are or are to be paid for wholly in cash.
These provisions may be disapplied by a special resolution of the shareholders,
either generally or specifically, for a maximum period not exceeding five
years, although in the case of companies whose shares are quoted on the
Official List of the London Stock Exchange, the disapplications do not
generally last longer than 15 months from the date of the resolution or, if
earlier, the date of the next annual general meeting. With respect to future
issuances of ordinary shares or ADSs that are or are to be paid for wholly in
cash and except to the extent already disapplied, shareholders will have to
approve the disapplication of preemptive rights.

Variation of Rights

   If at any time the share capital of Shire is divided into different classes
of shares, the rights attached to any class may be varied or abrogated, subject
to the provisions of the Companies Act, in the manner as may be provided by
those rights or, in the absence of such a provision, either with the written
consent of the holders of at least three-fourths of the nominal amount of the
issued shares of the class or with the sanction of any extraordinary resolution
passed at a separate general meeting of the holders of the issued shares of
that class but not otherwise. At every such separate meeting, the quorum shall
be two persons present in person holding or representing by proxy at least one-
third in nominal amount of the issued shares of the class or, at an adjourned
meeting, any holder of the shares in question whether present in person or by
proxy. The rights conferred upon the holders of any class of shares shall not,
unless expressly attached to the terms of issuance of the shares, be determined
to be altered by the creation or issuance of further shares ranking pari passu
with those shares.

Alteration of Capital

   Subject to the provisions of the Companies Act and to any special rights
previously conferred on the holders of any existing shares, any share may be
issued with or have attached to it the rights and restrictions as Shire may
determine by ordinary resolution or, if no resolution has been passed, as the
board of directors may decide. Redeemable shares may be issued subject to the
provisions of the Companies Act and to any rights conferred on the holders of
any class of existing shares.

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<PAGE>

   Shire may by ordinary resolution:

  .increase its share capital;

  . consolidate and divide all or any of its share capital into shares of a
    larger amount than its existing shares;

  . subject to the provisions of the Companies Act, subdivide all or any of
    its shares into shares of a smaller nominal amount and decide that the
    shares resulting from the subdivision have among themselves a preference
    or other advantage or are subject to a restriction; and

  . cancel any shares which have not been taken or agreed to be taken by any
    person and diminish the amount of its authorized share capital by the
    amount of the shares so canceled.

   Subject to the provisions of the Companies Act and the rights attached to
existing shares, Shire may by special resolution reduce its authorized and
issued share capital, any capital redemption reserve and any share premium
account in any manner. Shire may also, subject to the requirements of the
Companies Act and to the rights conferred on holders of any class of shares,
purchase all or any of its own shares, including any redeemable shares.

Disclosure of Interests

   Section 198 of the Companies Act provides that a person, including a company
and other legal entities, that acquires an interest of 3.0% or more of any
class of shares, including through ADRs, comprising part of a company's issued
share capital carrying the right to vote in all circumstances at a general
meeting of such company is required to notify the company of its interest
within two days following the day on which the notification obligation arises.
After the 3.0% level is exceeded, similar notifications must be made in respect
of increases or decreases taking the shareholding above or below a whole
percentage figure. Interests held by some investment fund managers may be
disregarded for the purposes of calculating the 3.0% threshold, but the
disclosure obligation will still apply where those interests exceed 10% or more
of any class of Shire's relevant share capital and to increases or decreases
taking the shareholding above or below a whole percentage figure after that
time.

   For purposes of the notification obligation, the interest of a person in
shares means any kind of interest in shares including an interest in any
shares:

  .in which a spouse, or child or stepchild under the age of 18 is
     interested;

  .in which a corporate body is interested and either

   -- that corporate body or its directors are generally accustomed to act
     in accordance with that person's directions or instructions or

   -- that person controls one-third or more of the voting power of that
     corporate body; or

  . in which another party is interested and the person and that other party
    are parties to a "concert party" agreement under Section 204 of the
    Companies Act. An agreement is a "concert party" agreement if:

   -- it provides for one or more parties to acquire interests in shares of
     a particular company,

   -- it imposes obligations or restrictions on any one or more of the
     parties as to the use, retention or disposal of the interests acquired
     under the agreement and

   -- any interest in Shire's shares is in fact acquired by any of the
     parties under the agreement.

   In addition, Section 212 of the Companies Act provides that a public company
may by written notice require a person whom the company knows or has reasonable
cause to believe to be, or to have been at any time during the three years
immediately preceding the date on which the notice is issued, interested in
shares comprised in the company's issued share capital carrying the right to
vote in all circumstances at a general meeting of such company to confirm that
fact or to indicate whether or not that is the case, and where such person
holds or during the relevant time had held an interest in those shares, to give
such further information as may be required relating to that interest and any
other interest in the shares of which that person is aware.

                                       88
<PAGE>

   Where notice is served by a company under the foregoing provisions on a
person who is or was interested in shares of the company and that person fails
to give the company any information required by the notice within the time
specified in the notice, the company may apply to the English court for an
order directing that the shares in question be subject to restrictions
prohibiting, among other things, any transfer of those shares, the exercise of
the voting rights in respect of those shares, the taking up of rights in
respect of those shares and, other than in liquidation, payments in respect of
those shares.

   A person who fails to fulfill the obligation imposed by Sections 198 to 202
and 212 of the Companies Act described above is subject to criminal penalties.

Share Acquisitions

   The City Code on Takeovers and Mergers, issued and administered by the Panel
on Takeovers and Mergers in London, is applicable to Shire because Shire is a
public limited company incorporated and resident in England and Wales. The City
Code is intended to operate principally to ensure fair and equal treatment of
all shareholders in companies to which it applies. When persons hold or acquire
certain percentages of voting rights of a U.K. public company such as Shire,
these persons may be required, in certain circumstances, to make an offer to
all shareholders of that company for its shares. For purposes of the City Code,
the term persons includes all persons "acting in concert" as that term is
defined in the City Code.

Transfer of Shares

   Any holder of ordinary shares may transfer all or any of those shares in the
manner authorized by the Stock Transfer Act 1963. The instrument of transfer
shall be signed by or on behalf of the transferor and, in the case of a partly
paid share, by or on behalf of the transferee. The transferor shall be deemed
to remain the holder of the share until the name of the transferee is entered
in the register of members of Shire in respect of it.

   The directors may, in their absolute discretion and without assigning any
reason, refuse to register any transfer of shares unless:

  . it is in respect of a fully paid share; provided that where any nil paid
    or partly paid shares are admitted to the Official List of the London
    Stock Exchange, such discretion may not be exercised in such a way as to
    prevent dealings in such shares taking place on an open and proper basis;

  . it is duly stamped, is lodged with Shire and is accompanied by the
    certificate for the shares to which it relates and such other evidence as
    the directors may reasonably require to show the right of the transferor
    to make the transfer;

  . it is in respect of only one class of shares;

  . it is in favor of not more than four transferees; and

  . it is in respect of a share on which Shire has no lien.

   Notwithstanding anything in the Articles to the contrary, any shares in
Shire may be issued, held, registered, converted to, transferred or otherwise
dealt with in uncertificated form and converted from uncertificated form to
certificated form in accordance with The Uncertificated Securities Regulations
1995 (SI 1995/3272) including any modification of and rules made under those
provisions or any regulations in substitution for those provisions made under
Section 207 of the Companies Act 1989 for the time being in force and practices
instituted by an operator of the relevant system. Any provision of the Articles
shall not apply to any uncertificated shares to the extent that those
provisions are inconsistent with:

  . the holding of shares in uncertificated form;

  . the transfer of title of shares by means of a relevant system; or

  . any provision of the regulations referred to in this paragraph.

                                       89
<PAGE>

Other Shares Information

   There are currently no U.K. foreign exchange controls on the payment of
dividends on the ordinary shares or the conduct of Shire's operations. There
are no restrictions under Shire's Memorandum and Articles of Association or
under English law that limit the right of non-resident or foreign owners to
hold or vote Shire's ordinary shares. However, no shareholders are entitled to
receive notices from Shire, including notices of shareholders' meetings, unless
they have given an address in the U.K. to Shire to which those notices may be
sent. Notwithstanding the foregoing, Shire provides information to the
depositary, which in turn forwards that information to the holders of ADSs.

                                       90
<PAGE>

                   DESCRIPTION OF AMERICAN DEPOSITARY SHARES
                        AND AMERICAN DEPOSITARY RECEIPTS

American Depositary Shares and American Depositary Receipts

   Morgan Guaranty Trust Company of New York as depositary will issue the ADSs
which you will be entitled to receive pursuant to the merger. Each ADS will
represent ownership interest in three shares which we will deposit with the
custodian under the deposit agreement among Shire, the depositary and yourself
as an ADR holder. In the future, each ADS will also represent any securities,
cash or other property deposited with the depositary but not distributed by
them directly to you. Your ADSs will be evidenced by what are known as American
depositary receipts. An ADR may be issued in either book-entry or certificated
form by the depositary. If an ADR is issued in book-entry form, you will
receive periodic statements from the depositary showing your ownership interest
in ADSs.

   The depositary's office is located at 60 Wall Street, New York, NY 10260.

   You may hold ADSs either directly or indirectly through your broker or other
financial institution. If you hold ADSs directly, you are an ADR holder. This
description assumes you hold your ADSs directly. If you hold the ADSs through
your broker or financial institution nominee, you must rely on the procedures
of such broker or financial institution to assert the rights of ADR holders
described in this section. You should consult with your broker or financial
institution to find out what those procedures are.

   Because the depositary's nominee will actually be the registered owner of
the shares, you must rely on it to exercise the rights of a shareholder on your
behalf. The obligations of the depositary and its agents are set out in the
deposit agreement. The deposit agreement and the ADSs are generally governed by
New York law.

   The following is a summary of the material terms of the deposit agreement.
Because it is a summary, it does not contain all the information that may be
important to you. For more complete information, you should read the entire
deposit agreement and the form of ADR which contains the terms of your ADSs.
You can read a copy of the deposit agreement which is filed as an exhibit to
the registration statement of which this Prospectus-Proxy Statement forms a
part. You may also copy the deposit agreement, which is located at the SEC's
Public Reference Room at 450 Fifth Street, N.W., Washington, D.C. 20549. You
may obtain information on the operation of the Public Reference Room by calling
the SEC at 1-800-732-0330.

Share Dividends and Other Distributions

 How will I receive dividends and other distributions on the Shares underlying
 my ADSs?

   The depositary has agreed to pay to you the cash dividends or other
distributions it or the custodian receives on shares or other deposited
securities, after deducting its expenses. You will receive these distributions
in proportion to the number of underlying shares your ADSs represent.

   Shire may make various types of distributions with respect to its
securities. Except as stated below, to the extent the depositary is legally
permitted it will deliver such distributions to ADR holders in proportion to
their interests in the following manner:

  . Cash. The depositary shall convert cash distributions from foreign
    currency to U.S. dollars if this is permissible and can be done on a
    reasonable basis. The depositary will endeavor to distribute such cash in
    a practicable manner, and may deduct any taxes required to be withheld,
    any expenses of converting foreign currency and transferring funds to the
    U.S., and certain other expenses and adjustments. In addition, before
    making a distribution the depositary will deduct any taxes withheld. If
    the exchange rates fluctuate during a time when the depositary cannot
    convert the currency, you may lose some or all of the value of the
    distribution.

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  . Shares. In the case of a distribution in shares, the depositary will
    issue additional ADRs to evidence the number of ADSs representing such
    shares. Only whole ADSs will be issued. Any shares which would result in
    fractional ADSs will be sold and the net proceeds will be distributed to
    the ADR holders entitled thereto.

  . Rights to receive additional shares. In the case of a distribution of
    rights to subscribe for additional shares or other rights, if Shire
    provides satisfactory evidence that the depositary may lawfully
    distribute such rights, the depositary may arrange for ADR holders to
    instruct the depositary as to the exercise of such rights. However, if
    Shire does not furnish such evidence, the depositary may

   .sell such rights if practicable and distribute the net proceeds as cash,
      or

   .allow such rights to lapse, whereupon ADR holders will receive nothing.

  Shire has no obligation to file a registration statement under the
  Securities Act in order to make any rights available to ADR holders.

  . Other Distributions. In the case of a distribution of securities or
    property other than those described above, the depositary may either (i)
    distribute such securities or property in any manner it deems fair and
    equitable or (ii) sell such securities or property and distribute any net
    proceeds in the same way it distributes cash.

   Any U.S. dollars will be distributed by checks drawn on a bank in the U.S.
for whole dollars and cents. Fractional cents will be withheld without
liability for interest and added to future cash distributions.

   The depositary may choose any practical method of distribution for any
specific ADR holder, including the distribution of foreign currency, securities
or property, or it may retain such items, without paying interest on or
investing it, on behalf of the ADR holder as deposited securities.

   The depositary may not be able to convert any currency at a specified
exchange rate or sell any property, rights, shares or other securities at a
specified price. We cannot assure you that any of such transactions can be
completed within a specified time period.

Deposit, Withdrawal and Cancellation

 How does the depositary issue ADSs?

   The depositary will issue ADSs if you or your broker deposit shares or
evidence of rights to receive shares with the custodian. In the case of the
ADSs to be issued pursuant to the merger, Shire will arrange to deposit such
shares.

   Shares deposited in the future with the custodian must be accompanied by
certain documents, including instruments showing that such shares have been
properly transferred or endorsed to the person on whose behalf the deposit is
being made.

   The custodian will hold all deposited shares for the account of the
depositary. This includes those shares being deposited by or on behalf of Shire
in connection with the merger. ADR holders thus have no direct ownership
interest in the shares and only have such rights as are contained in the
deposit agreement. The custodian will also hold any additional securities,
property and cash received on or in substitution for the deposited shares. The
deposited shares and any such additional items are referred to as "deposited
securities".

   Upon each deposit of shares, receipt of related delivery documentation and
compliance with the other provisions of the deposit agreement, including the
payment of the fees and charges of the depositary, the depositary will issue an
ADR or ADRs in the name of the person entitled thereto evidencing the number of
ADSs to which such person is entitled. Certificated ADRs will be delivered at
the depositary's principal New York office or any other location that it may
designate as its transfer office. If ADRs are in book-entry

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form, a statement setting forth such ownership interest will be mailed to
holders by the depositary. All of the ADSs issued outside of the merger will,
unless specifically requested to the contrary, be part of the depositary's
book-entry direct registration system and registered holders will receive
periodic statements from the depositary which will show the number of ADSs
registered in such holder's name. An ADR holder can always request that the
ADSs not be held through the depositary's direct registration system and that a
certificated ADR be issued.

 How do ADR holders cancel an ADS and obtain deposited securities?

   When you turn in your ADS at the depositary's office, it will, upon payment
of certain applicable fees, charges and taxes, deliver at the custodian's
office the underlying shares. At your risk, expense and request, the depositary
may deliver at such other place as you may request.

   The depositary may only restrict the withdrawal of deposited securities in
connection with:

  . temporary delays caused by closing transfer books of the depositary or
    Shire or the deposit of shares in connection with voting at a
    shareholders' meeting, or the payment of dividends,

  .the payment of fees, taxes and similar charges, or

  .compliance with any U.S. or foreign laws or governmental regulations
     relating to the ADRs.

   This right of withdrawal may not be limited by any other provision of the
agreement.

Voting Rights

 How do I vote?

   If you are an ADR holder and the depositary asks you to provide it with
voting instructions, you may instruct the depositary how to exercise the voting
rights for the shares which underlie your ADSs. After receiving voting
materials from Shire, the depositary will notify all of the ADR holders of any
shareholder meeting or solicitation of consents or proxies. This notice will
describe how you may instruct the depositary to exercise the voting rights for
the shares which underlie your ADSs. For instructions to be valid, the
depositary must receive them on or before the date specified. The depositary
will try, as far as practical, subject to the provisions of and governing the
underlying shares or other deposited securities, to vote or to have its agents
vote the shares or other deposited securities as you instruct. The depositary
will only vote or attempt to vote as you instruct. The depositary will not
itself exercise any voting discretion. Furthermore, neither the depositary nor
its agents are responsible for any failure to carry out any voting
instructions, for the manner in which any vote is cast or for the effect of any
vote.

   Because there is no guarantee that you will receive voting materials in time
to instruct the depositary to vote, it is possible that you, or persons who
hold their ADSs through brokers, dealers or other third parties, will not have
the opportunity to exercise a right to vote.

Fees and Expenses

 What fees and expenses will I be responsible for paying?

   ADR holders will be charged a fee for each issuance of ADSs after the
initial issuance of ADSs, including issuances resulting from distributions of
shares, rights and other property, and for each surrender of ADSs in exchange
for deposited securities. The fee in each case is $5.00 for each 100 ADSs or
any portion thereof issued or surrendered. ADR holders or persons depositing
shares may also be charged the following expenses:

  .stock transfer or other taxes and other governmental charges;

  .cable, telex and facsimile transmission and delivery charges;

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  . transfer or registration fees for the registration of transfer of
    deposited securities on any applicable register in connection with the
    deposit or withdrawal of deposited securities; and

  .expenses of the depositary in connection with the conversion of foreign
     currency into U.S. dollars.

   Shire will pay all other charges and expenses of the depositary and any
agent of the depositary pursuant to agreements from time to time between Shire
and the depositary. However, Shire will not pay any charges and expenses of
the custodian. The fees described above may be amended from time to time.

Payment of Taxes

   ADR holders must pay any tax or other governmental charge payable by the
custodian or the depositary on any ADS or ADR, deposited security or
distribution. If an ADR holder owes any tax or other governmental charge, the
depositary may (1) deduct the amount thereof from any cash distributions, or
(2) sell deposited securities and deduct the amount owing from the net
proceeds of such sale. In either case the ADR holder remains liable for any
shortfall. Additionally, if any tax or governmental charge is unpaid, the
depositary may also refuse to effect any registration, registration of
transfer, split-up or combination of deposited securities or any withdrawal of
deposited securities, except under limited circumstances mandated by
securities regulations. If any tax or governmental charge is required to be
withheld on any non-cash distribution, the depositary may sell the distributed
property or securities to pay such taxes and distribute any remaining net
proceeds to the ADR holders entitled thereto.

Reclassifications, Recapitalizations and Mergers

   If Shire takes certain actions that affect the deposited securities,
including (i) any change in par value, split-up, consolidation, cancellation
or other reclassification of deposited securities and (ii) any
recapitalization, reorganization, merger, consolidation, liquidation,
receivership, bankruptcy or sale of all or substantially all the assets of
Shire, then the depositary may choose to:

       1) amend the form of ADR;

       2) distribute additional or amended ADRs;

       3) distribute cash, securities or other property it has received in
    connection with such actions;

       4) sell any securities or property received and distribute the
    proceeds as cash; or

       5) none of the above.

   If the depositary does not choose any of (1)--(4), any of the cash,
securities or other property it receives shall constitute part of the
deposited securities and each ADS will then represent a proportionate interest
in such property.

Amendment and Termination

 How may the deposit agreement be amended?

   Shire may agree with the depositary to amend the deposit agreement and the
ADSs without your consent for any reason. ADR holders must be given at least
30 days notice of any amendment that imposes or increases any fees or charges,
other than taxes and other charges specifically payable by ADR holders under
the deposit agreement, or affects any substantial existing right of ADR
holders. If an ADR holder continues to hold ADRs or ADSs after being so
notified, such ADR holder is deemed to agree to such amendment. An amendment
can become effective before notice is given if this is necessary to ensure
compliance with a new law, rule or regulation.

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   No amendment will impair your right to surrender your ADSs and receive the
underlying securities. If a governmental body adopts new laws or rules which
require the deposit agreement or ADS to be amended, we and the depositary may
make the necessary amendments, which could take effect before you receive
notice thereof.

 How may the deposit agreement be terminated?

   The depositary may terminate the deposit agreement by giving the ADR
holders at least 30 days prior notice, and it must do so at Shire's request.
After termination, the depositary's only responsibility will be (i) to deliver
deposited securities to ADR holders who surrender their ADRs, and (ii) to hold
or sell distributions received on deposited securities. As soon as practicable
after the expiration of six months from the termination date, the depositary
will sell the deposited securities which remain and hold the net proceeds of
such sales, without liability for interest, in trust for the ADR holders who
have not yet surrendered their ADRs. After making such sale, the depositary
shall have no obligations except to account for such proceeds and other cash.

Limitations on Obligations and Liability to ADR Holders

 Limits on Shire's Obligations and the Obligations of the Depositary; Limits
 on Liability to ADR Holders and Holders of ADSs

   The deposit agreement expressly limits the obligations and liability of the
depositary, Shire and its respective agents. Neither Shire nor the depositary
will be liable:

  . if Shire or the depositary is prevented or hindered in performing any
    obligation by circumstances beyond its control, including, without
    limitation, requirements of law, rule, regulation, the terms of the
    deposited securities, and acts of God;

  .for exercising or failing to exercise discretion under the deposit
     agreement;

  .if Shire or the depositary performs its obligations without gross
     negligence or bad faith; or

  . for any action based on advice or information from legal counsel,
    accountants, any person presenting shares for deposit, any holder, or
    other qualified person.

   Neither the depositary nor its agents have any obligation to appear in,
prosecute or defend any action, suit or other proceeding in respect of any
deposited securities or the ADRs. Shire and its agents shall only be obligated
to appear in, prosecute or defend any action, suit or other proceeding in
respect of any deposited securities or the ADRs, which in Shire's opinion may
involve it in expense or liability, if indemnity satisfactory to it against
all expense, including fees and disbursements of counsel, and liability be
furnished as often as Shire requires.

   The depositary will not be responsible for failing to carry out
instructions to vote the ADSs or for the manner in which the ADSs are voted or
the effect of the vote.

   The depositary may own and deal in securities and in ADSs.

Requirements for Depositary Actions

   Shire, the depositary or the custodian may refuse to

  .issue, register or transfer an ADR or ADRs,

  .effect a split-up or combination of ADRs,

  .deliver distributions on any such ADRs, or

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  . unless the deposit agreement provides otherwise, permit the withdrawal of
    deposited securities, until the following conditions have been met:

   -- the holder has paid all taxes, governmental charges, and fees and
     expenses as required in the deposit agreement;

   -- the holder has provided the depositary with any information it may
     deem necessary or proper, including, without limitation, proof of
     identity and the genuineness of any signature; and

   -- the holder has complied with such regulations as the depositary may
     establish under the deposit agreement.

   Unless the deposit agreement provides otherwise, the depositary may also
suspend the issuance of ADSs, the deposit of shares, the registration,
transfer, split-up or combination of ADRs, or the withdrawal of deposited
securities if the register for ADRs or any deposited securities is closed or if
the depositary or Shire decides any such action is advisable.

Pre-release of ADSs

   The depositary may also issue ADRs prior to the deposit with the custodian
of shares or rights to receive shares. This is called a pre-release of the ADS.
A pre-release is closed out as soon as the underlying shares are delivered to
the depositary. The depositary may pre-release ADSs only if:

  .the depositary has received collateral for the full market value of the
     pre-released ADRs; and

  .each recipient of pre-released ADRs agrees in writing that he or she

   -- owns the underlying shares,

   -- assigns all rights in such shares to the depositary,

   -- holds such shares for the account of the depositary and

   -- will deliver such shares to the custodian as soon as practicable, and
     promptly if the depositary so demands.

   In general, the number of pre-released ADSs will not evidence more than 30%
of all ADSs outstanding at any given time, excluding those evidenced by pre-
released ADRs. However, the depositary may change or disregard such limit from
time to time under certain circumstances.

The Depositary

 Who is the depositary?

   Morgan Guaranty Trust Company of New York, a New York banking corporation,
is a commercial bank offering a wide range of banking and trust services to its
customers in the New York metropolitan area, throughout the U.S. and around the
world.

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       COMPARATIVE RIGHTS OF ROBERTS SHAREHOLDERS AND SHIRE SHAREHOLDERS

   As a result of the merger, Roberts shareholders will receive, at their
option, either ADSs or ordinary shares of Shire, a public limited company
incorporated under the laws of England and Wales. The following is a summary of
the material differences between the current rights of Shire shareholders and
Roberts shareholders under English law and the New Jersey Business Corporation
Act, respectively, and under Roberts' Certificate of Incorporation and By-laws
and Shire's Memorandum and Articles of Association. The following summary does
not purport to be a complete description of the rights of shareholders of Shire
and shareholders of Roberts under, and is qualified in its entirety by
reference to, relevant English law, the New Jersey Business Corporation Act,
Roberts' Certificate of Incorporation and By-laws and Shire's Memorandum or
Articles of Association. For information as to where the governing instruments
of Roberts and Shire may be obtained, see "Where You Can Find More
Information."

Authorized Capital Stock

   The authorized capital stock of Roberts currently consists of 100,000,000
shares of common stock, $.01 par value per share, and 10,000,000 shares of
Class B Preferred Stock, $.01 par value per share.

   The authorized share capital of Shire currently consists of
(Pounds)10,000,000 divided into 200,000,000 ordinary shares.

Shareholder Voting Rights

   Under the New Jersey Business Corporation Act, each outstanding share is
entitled to one vote on each matter submitted to a vote at a shareholders
meeting unless the certificate of incorporation provides otherwise. A majority
of the shares present at a meeting or represented by proxy constitutes a
quorum. In addition, the certificate of incorporation may provide for
cumulative voting at all elections of directors of the corporation. Roberts'
Certificate of Incorporation does not provide for cumulative voting.

   Under English law, a shareholder entitled to vote at a shareholders' meeting
is entitled to one vote on a show of hands regardless of the number of shares
he or she holds; provided, however, that any group of five ordinary
shareholders and any shareholder representing at least 10% of the voting rights
of all the members having the right to vote at the meeting have the statutory
right to demand a vote by a poll, which means that each ordinary shareholder
would be entitled to one vote for each ordinary share held by the shareholder.
The number and percentage of shareholders referred to in the preceding sentence
may be set lower in a company's articles of association. Shire's Articles of
Association do not allow a poll to be demanded by a lower number of
shareholders or a shareholder holding a lower percentage of the ordinary shares
than that designated under English law. Shire's Articles of Association specify
that two members present in person or by proxy and entitled to vote shall be a
quorum. Cumulative voting is not recognized under English law.

Special Meetings of Shareholders

   New Jersey law provides that a special meeting of shareholders may be called
by the president or the board of directors, or by any shareholder, director or
officer as may be provided in the bylaws. Roberts' By-laws provide that the
Chairman of the Board, the board of directors and the President may call a
special meeting. Upon application of the holder or holders of not less than ten
(10) percent of all the shares entitled to vote at a meeting, the Superior
Court of New Jersey, for good cause shown, may order that a special meeting be
called.

   Under English law, an extraordinary general meeting of shareholders may be
called by the board of directors or shareholders holding at least one-tenth of
the paid-up capital of the company carrying voting rights at general meetings.
An ordinary resolution requires 14 days' clear notice, an extraordinary
resolution requires 14 days' clear notice and a special resolution requires 21
days' clear notice. In addition, in the case of an

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annual general meeting, all the shareholders who are permitted to attend and
vote may agree to a shorter notice period. In the case of an extraordinary
general meeting, a majority of the shareholders holding at least 95% by nominal
value of the shares which can be voted at the meeting can agree to a shorter
notice period. Extraordinary resolutions are relatively unusual and are
confined to matters out of the ordinary course of business, such as a proposal
to wind up the affairs of the company. Special resolutions generally involve
proposals to:

  .change the name of the company;

  .alter its capital structure;

  .change or amend the rights of shareholders;

  .permit the company to issue new shares for cash without applying the
     shareholders' preemptive rights;

  .amend the company's objects or purpose clause in its memorandum of
     association;

  .amend the company's articles of association; or

  . carry out other matters for which the company's articles of association or
    the Companies Act prescribe that a special resolution is required.

All other proposals relating to the ordinary course of the company's business,
such as the election of directors and transactions, such as mergers,
acquisitions and dispositions, are the subject of an ordinary resolution.

Consent of Shareholders in Lieu of Meeting

   Under New Jersey law, except as otherwise provided by the corporation's
certificate of incorporation, any action required or permitted to be taken at a
shareholders meeting may be taken by written consent without a meeting, without
prior written notice and without a vote. Except for the annual election of
directors which requires the written consent to be unanimous, such action may
be taken upon the written consent of the holders of the minimum number of votes
that would be required to authorize the action at a meeting at which all
shareholders entitled to vote were present and voting.

   Under English law, shareholders of a public company such as Shire are not
permitted to pass resolutions by written consent.

Rights of Inspection

   Under New Jersey law, any shareholder may upon written request receive a
copy of the corporation's balance sheet as at the end of the preceding fiscal
year and its profit and loss and surplus statement for such fiscal year. In
addition, New Jersey law grants the right to inspect and make extracts from a
corporation's minutes of shareholder proceedings and its record of shareholders
only for any proper purpose:

  .to shareholders of record for at least 6 months preceding the demand;

  . to holders of at least 5% of the outstanding shares of any class or
    series of the corporation's stock upon five days written demand; or

  .to shareholders upon receipt of court order.

   Except when closed under the provisions of the Companies Act, the register
and index of names of shareholders of an English company may be inspected
during business hours for free, by its shareholders, or for a fee by any other
person. In both cases, the documents may be copied for a fee. The shareholders
of an English public company may also inspect, without charge, during business
hours minutes of meetings of the shareholders and obtain copies of the minutes
for a fee, and service contracts of the company's directors, if the contracts
have an unexpired term of more than 12 months or require more than 12 months'
notice to terminate. In addition, the published annual accounts of a public
company are required to be available for shareholders at a general meeting and
a shareholder is entitled to a copy of these accounts.

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   A Shire member, other than a director or officer, has no rights to inspect
an accounting record or other document except if he is authorized by the board.
The accounting records shall be kept at the office or at another place decided
by the board and shall be available during business hours for the inspection of
the directors and other officers.

Amendment of Governing Instruments

   Generally, a New Jersey corporation's board of directors may approve, and
its shareholders may adopt, one or more amendments to its certificate of
incorporation upon the affirmative vote of the majority of the votes cast by
the holders of shares entitled to vote thereon, unless a greater requirement is
specified in the certificate of incorporation. Except for the two-thirds voting
standard required for certain business combinations, Roberts' Certificate of
Incorporation requires the affirmative vote of a majority of votes cast at a
meeting at which a quorum is present. In some limited circumstances, however,
the board of directors may make amendments to the certificate of incorporation
without shareholder approval.

   New Jersey law provides that a board of directors has the power to make,
alter and repeal a corporation's bylaws, unless such power is reserved to the
corporation's shareholders in the corporation's certificate of incorporation,
but bylaws made by the board of directors may be altered or repealed, and new
bylaws may be made by the shareholders of a corporation. Roberts' By-laws
provide for alteration or amendment of the corporation's By-laws by the board
of directors or by shareholders.

   Under English law, shareholders have the power to amend the objects or
purpose clause in a company's memorandum of association and any provisions of
the company's articles of association by special resolution, subject to, in the
case of amendments to the objects clause of the memorandum of association, the
right of dissenting shareholders to apply to the courts to cancel the
amendments. Under English law, the board of directors is not authorized to
change the memorandum of association or the articles of association. Amendments
affecting the rights of the holders of any class of shares may, depending on
the rights attached to the class and the nature of the amendments, also require
approval by extraordinary resolution of the classes affected in separate class
meetings.

Certain Provisions Relating to Share Acquisition

   The New Jersey Business Corporation Act generally prevents a New Jersey
corporation from entering into certain business combinations, including certain
mergers, dispositions of assets or shares and recapitalizations, with an
interested shareholder, unless:

  . the corporation's board of directors approved the business combination or
    transaction prior to the time the shareholder became an interested
    shareholder; or

  . after the expiration of five years from the time at which the shareholder
    became an interested shareholder, (i) the business combination is
    approved by the board of directors and by a vote of two-thirds of the
    outstanding voting stock not owned by the interested shareholder or (ii)
    the business combination provides for the interested shareholder to pay a
    price calculated pursuant to a formula designed to ensure that all other
    shareholders receive at least the highest price per share to be paid by
    such interested shareholder.

   An interested shareholder is defined as any person or entity that is the
beneficial owner of at least 10% of a corporation's voting stock or an
affiliate or associate of the corporation who was the owner of 10% or more of
the corporation's voting stock at any time in the preceding five years.

   In the case of a company listed on the London Stock Exchange, shareholder
approval must be obtained for certain acquisitions or disposals of assets
involving directors or substantial shareholders or their associates. In
addition, takeovers of public companies, which are generally those listed on
the London Stock Exchange, are regulated by the City Code, which is comprised
of non-statutory rules unenforceable at law, and administered

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by the Takeover Panel, a body consisting of representatives of City of London
financial and professional institutions which oversees the conduct of take-
overs. The City Code provides that when any person acquires, whether by a
series of transactions over a period of time or not, shares which, together
with shares held or acquired by persons acting in concert with him, represent
30% or more of the voting rights of a public company or any person, together
with persons acting in concert with him, holds at least 30% but not more than
50% of the voting rights and that person, or any person acting in concert with
him, acquires any additional shares, the person must generally make an offer
for all of the equity shares of the company, whether voting or non-voting, and
any class of voting non-equity shares of the company held by that person or any
person acting in concert with him, for cash, or accompanied by a cash
alternative, at not less than the highest price paid by the person or these
persons for the relevant shares during the 12 months preceding the date of the
offer.

Shareholder Rights Plan

   Roberts has entered into a Rights Agreement, dated as of December 16, 1996,
between Roberts and Continental Stock Transfer & Trust Company, as Rights
Agent, as amended, pursuant to which Roberts has issued rights to purchase its
Class B--Series A Junior Participating Preferred Stock. Roberts has taken all
action necessary to render the rights issued pursuant to the terms of the
Rights Agreement inapplicable to the merger and the related agreements and
transactions. In addition, Roberts has amended the Rights Agreement to change
the threshold of share ownership from 15% to 10% in determining whether a
Roberts shareholder shall be deemed an "Acquiring Person" under the Rights
Agreement.

   Shire does not have a shareholder rights plan.

Dissenters' Rights

   Under New Jersey law, with certain exceptions, a shareholder is entitled to
dissent from, and obtain payment of the fair value of the shareholder's shares
in the event of, a merger or a consolidation to which the corporation is a
party. Unless the certificate of incorporation provides otherwise, dissenters'
rights do not apply to holders of shares of any class or series if (i) such
class or series is listed on a national securities exchange or held of record
by not less than 1,000 holders, or shareholders receive in such transaction
cash and/or securities which are listed on a national securities exchange or
held of record by not less than 1,000 shareholders, or (ii) no vote of the
corporation's shareholders is required for effecting the proposed merger or
consolidation. Roberts' Certificate of Incorporation does not alter the
dissenters' rights provided for under New Jersey law.

   While English law does not generally provide for dissenters' rights, a
shareholder may apply to a court for an order on the ground that the relevant
company's affairs are being or have been conducted in a manner which is
unfairly prejudicial to the interests of its members generally or some part of
its members or that any proposed act or omission of the company is or would be
so prejudicial and the court may make such order as it thinks fit for giving
relief in respect of the matters complained of. In addition, in the context of
a takeover regulated by the City Code, where the person making the relevant
acquisition has given notice to the holders of any shares to which the takeover
relates that such person desires to acquire those shares, a holder may apply
for an order from the court that the person making the acquisition shall not be
bound and entitled to acquire those shares or ask the court to specify terms of
acquisition different from those of the takeover.

Disclosure of Interests

   There is no requirement under New Jersey law relating to the disclosure of
interests of shares held by a corporation's shareholders.

   The Companies Act provides that anyone who acquires an interest or becomes
aware that he has acquired an interest in 3% or more of any class of shares of
a public company's issued share capital carrying rights to vote at general
shareholder meetings must notify that company in writing of his interest within
two days. Thereafter, any increase or decrease of a whole percentage or
decrease which reduces the interest to below 3%

                                      100
<PAGE>

must be notified in writing to the company. In addition, the Companies Act
provides that a public company may, by notice in writing, require a person whom
the company knows or reasonably believes to be or to have been within the three
preceding years, interested in the company's issued voting share capital to
confirm whether this is or is not the case, and if this is the case, to give
further information that the company requires relating to his interest and any
other interest in the company's shares of which he is aware. The disclosure
must be made within a reasonable period as specified in the relevant notice
which may be as short as one or two days. When a notice is served by a company
on a person who is or was interested in shares of the company and that person
fails to give the company any information required by the notice within the
time specified in the notice, the company may apply to the court for an order
directing that the shares in question be subject to restrictions prohibiting,
among other things, any transfer of the shares, the exercise of voting rights,
the issue of further shares, and, other than in a liquidation, dividends and
other payments. These restrictions may also void any agreement to transfer the
shares.

   For the purpose of the above obligations, the interest of a person in shares
means, subject to certain exceptions, any kind of interest in shares including
interests in any shares:

  .in which his spouse, or his child or stepchild under the age of 18 is
     interested;

  . in which a corporate body is interested and either (i) that corporate
    body is or its directors are accustomed to act in accordance with that
    person's directions or instructions or (ii) that person controls one-
    third or more of the voting power of that corporate body; or

  . in which another party is interested and the person and that other party
    are parties to an agreement which provides for one or more parties to it
    to acquire interest in shares of the company, which imposes obligations
    or restrictions on any one or more of the parties as to the use,
    retention or disposal of such interests acquired pursuant to such
    agreement and pursuant to which any interest in the company's shares is
    in fact acquired by any of the parties. The holding of an ADR evidencing
    an ADS would generally constitute an interest in the underlying ordinary
    shares.

Sources and Payment of Dividends

   New Jersey law prohibits a corporation from making a distribution to its
shareholders if, after giving effect to such distribution, the corporation
would be unable to pay its debts as they become due in the usual course of
business or the corporation's total assets would be less than its total
liabilities.

   Subject to the prior rights of holders of preferred shares, an English
company may pay dividends on its ordinary shares only out of its distributable
profits, defined as accumulated, realized profits less accumulated, realized
losses, and not out of share capital, which includes share premiums, which are
equal to the excess of the consideration for the issue of shares over the
aggregate nominal amount of such shares. Amounts credited to the share premium
account, however, may be used to pay up unissued shares which may then be
distributed to shareholders in proportion to their holdings. In addition, under
English law, Shire will not be permitted to make a distribution if, at the
time, the amount of its net assets is less than the aggregate of its issued and
paid-up share capital and undistributable reserves. Subject to these
limitations, the Shire board will have the power under the Shire memorandum and
articles of association to pay cash dividends.

Classification of the Board of Directors

   New Jersey law permits but does not require the adoption of a classified
board of directors with staggered terms under which a part of the board of
directors is elected each year. Under New Jersey law, the authorization for a
classified board of directors must be included in the corporation's certificate
of incorporation or an amendment thereto. Additionally, the maximum term of
each class of directors is five years. Neither the Roberts Certificate of
Incorporation nor any amendment to the Certificate contains a provision for the
adoption of a classified board of directors of Roberts. New Jersey law allows
the board of directors, by resolution adopted by a majority of the entire
board, to designate an executive committee or other committee or

                                      101
<PAGE>

committees, each consisting of one or more members of the board, with the power
and authority, to the extent permitted by law, to act on behalf of the entire
board if the certificate or bylaws so provide. Roberts' By-laws authorize the
designation of one or more committees that will have and may exercise the
powers of the board of directors in the management of the business and affairs
of the corporation, except as proscribed by statute.

   English law permits a company to provide for the classification of the board
of directors with respect to the term of office that any director may hold.
Shire's Articles do not provide for such classification of the Shire board of
directors. Shire's Articles require that at each annual general meeting one-
third of the directors who are subject to retirement by rotation or, if their
number is not three or a multiple of three, the number nearest to but not
exceeding one-third, shall retire from office. If there are fewer than three
directors who are subject to retirement by rotation, one shall retire from
office. Subject to the Articles of Association, the directors to retire by
rotation at an annual general meeting include, so far as necessary to obtain
the number required, first, a director who wishes to retire and not offer
himself for reappointment, and, second, those directors who have been longest
in office since their last appointment or reappointment. Although this tri-
annual rotation is similar to a classified board, it is different in that any
director who is one of the one-third of directors who have been longest in
office since their last election or appointment at the time of the annual
meeting will retire from office regardless of the actual year of such
director's last appointment. A retiring director is eligible for re-election.

Removal of Directors

   In general, under New Jersey law, any or all of the directors of a
corporation may be removed for cause, or, unless otherwise provided in the
certificate of incorporation, without cause by the vote of a majority of the
votes cast by the holders of the shares then entitled to vote at an election of
directors; however, if the board of directors is classified, shareholders are
not entitled to remove directors without cause. Roberts' By-laws state that any
director or directors may be removed from office either with or without cause
by the shareholders by a majority of votes cast at a meeting at which a quorum
is present.

   Under the Companies Act, shareholders may remove a director without cause by
ordinary resolution, irrespective of any provisions of the company's articles
of association or service contract the director has with the company, provided
that 28 days' clear notice of the resolution is given to the company. Under the
Shire Articles of Association, Shire may by ordinary resolution remove a
director before the expiration of his period of office and may by ordinary
resolution appoint another person who is willing to act to be a director in his
place. A person appointed in this way is treated, for the purposes of
determining the time at which he or another director is to retire, as if he had
become a director on the date on which the person in whose place he is
appointed was last appointed or reappointed a director.

Vacancies on the Board of Directors

   Under New Jersey law, unless the certificate of incorporation or bylaws
provide otherwise, a vacancy, however caused, and newly created directorships
resulting from an increase in the authorized number of directors may be filled
by the affirmative vote of a majority of the remaining directors. In addition,
any directorship not filled by the board may be filled by the shareholders at a
shareholders meeting held for such purpose.

   Under English law, shareholders may by ordinary resolution, at a meeting at
which any director retires, appoint a person to be a director to fill a vacancy
or to become an additional director, subject to any maximum provided in the
company's articles of association. Shire's Articles of Association state that
there is no maximum number of directors. The board of directors has the power
to appoint a director to serve until the next general meeting of the company,
whereupon the director concerned is required to retire but will be eligible for
election.

                                      102
<PAGE>

Shareholders' Suits

   Under New Jersey law, a shareholder may institute a lawsuit on behalf of the
corporation. An individual shareholder also may commence a lawsuit on behalf of
himself and other similarly situated shareholders where the requirements for
maintaining a class action under New Jersey law have been met.

   While English law only permits a shareholder to initiate a lawsuit on behalf
of the company in limited circumstances, the Companies Act permits a
shareholder whose name is on the register of shareholders of the company to
apply for a court order when the company's affairs are being or have been
conducted in a manner unfairly prejudicial to the interests of all or some
shareholders, including the shareholder making the claim, or when any act or
omission of the company is or would be so prejudicial. A court has wide
discretion in granting relief , and may authorize civil proceedings to be
brought in the name of the company by a shareholder on terms that the court
directs. Except in these limited circumstances, English law does not generally
permit class action lawsuits by shareholders on behalf of the company or on
behalf of other shareholders.

Indemnification; Liability of Directors

   New Jersey law contains a provision and limitation regarding officers' and
directors' liability and regarding indemnification by a corporation of its
officers, directors, and employees. New Jersey law permits a New Jersey
corporation to include a provision in its certificate of incorporation which
eliminates or limits the personal liability of a director or officer to the
corporation or its shareholders for monetary damages for breach of fiduciary
duties as a director or officer. Roberts' Certificate of Incorporation limits
the liability of the directors and officers of Roberts to the fullest extent
permitted by law. However, New Jersey law prohibits the exculpation of
liability of a director or officer for any breach of duty based upon an act or
omission:

  .in breach of the director's or officer's duty of loyalty to the
     corporation or its shareholders;

  .not in good faith or involving a knowing violation of law; or

  .resulting in receipt by such person of an improper personal benefit.

   Under New Jersey law, corporations are also permitted to indemnify
directors, officers, employees and agents in certain circumstances and required
to indemnify directors under certain circumstances. Roberts' By-laws provide
that a director, officer, employee or agent shall, in general, be indemnified
by the corporation if he has acted in good faith and in a manner he reasonably
believed to be in, or not opposed to, the best interests of the corporation
and, with respect to any criminal action or proceeding, had no reasonable cause
to believe his conduct was unlawful. In addition, corporations must indemnify a
director to the extent the director has been successful on the merits or
otherwise. Under New Jersey law and Roberts' By-laws, Roberts may purchase
insurance on behalf of any director, officer, employee or agent for expenses
incurred in any proceeding and any liabilities asserted against that person,
whether or not Roberts would have the power to indemnify such person.

   English law does not permit a company to indemnify a director or officer of
the company, or any person employed by the company as an auditor, against any
liability arising from negligence, default, breach of duty or breach of trust
against the company, except that indemnification is allowed for liabilities
incurred in proceedings in which judgment is entered in favor of the director
or officer or the director or officer is acquitted, or the director or officer
is held liable, but the court finds that he acted honestly and reasonably and
that relief should be granted. The Companies Act enables companies to purchase
and maintain insurance for directors, officers and auditors against any
liability arising from negligence, default, breach of duty or breach of trust
against the company.

Preemptive Rights

   Under New Jersey law, shareholders have preemptive rights to purchase shares
only if the certificate of incorporation so provides. Roberts' Certificate of
Incorporation states that a holder of any shares of capital stock of Roberts
shall have preemptive rights to subscribe or to purchase any issuances of
capital stock of

                                      103
<PAGE>

Roberts only to the extent that, and on the terms and conditions upon which,
the Roberts board expressly grants in a written agreement between such holder
and Roberts. The Roberts board is given the authority to authorize the granting
of such preemptive rights to any holders of its capital stock.

   Under English law, the issuance for cash of equity securities, being those
which, with respect to dividends or capital, carry a right to participate
beyond a specified amount, or rights to subscribe for or convert into equity
securities must be offered first to the existing equity shareholders in
proportion to the respective nominal values of their holdings, unless a special
resolution to the contrary has been passed by shareholders in a general
meeting.

Rights of Purchase and Redemption

   New Jersey law prohibits a corporation from repurchasing or redeeming its
shares if:

  . after giving effect to such repurchase or redemption, the corporation
    would be unable to pay its debts as they become due in the usual course
    of business or the corporation's total assets would be less than its
    total liabilities;

  .after giving effect to such repurchase or redemption, the corporation
     would have no equity outstanding;

  .the redemption or repurchase price exceeded that specified in the
     securities acquired; or

  . such repurchase or redemption is contrary to any restrictions contained
    in the corporation's certificate of incorporation.

   Roberts' Certificate of Incorporation does not contain any provision
limiting the ability to repurchase or redeem shares.

   Under English law, a company may issue redeemable shares if authorized by
its memorandum and articles of association, subject to any conditions stated
therein. The Shire Memorandum and Articles of Association provide that shares
may be issued on terms that they are to be redeemed or are liable to be
redeemed. The Companies Act provides that, subject to some other of its
provisions, a limited company having a share capital may, if authorized by its
articles of association, purchase its own shares, including any redeemable
shares. A company may redeem or repurchase shares only if the shares are fully
paid and, in the case of public companies, only out of distributable profits,
or the proceeds of a new issue of shares made for the purpose of the repurchase
or redemption. In the case of an open-market purchase by a company of its own
shares, authority to make the market purchase must be given by an ordinary
resolution of the company's shareholders. That authority may be general or for
a specific transaction. A company may only make an off-market purchase of its
own shares in pursuance of a contract authorized by a special resolution. The
London Stock Exchange requires that where a company has issued shares which are
listed on the London Stock Exchange and are convertible into a class of shares
to be repurchased, the holders of the convertible shares must first pass an
extraordinary resolution approving any repurchase at a separate class meeting.
The London Stock Exchange requires that purchases pursuant to a general
authority of 15% or more of a company's share capital must be made through
either a tender or partial offer to all shareholders, at a stated maximum or
fixed price. Purchases pursuant to a general authority below the 15% threshold
may be made through the open market other than by tender or partial offer,
provided that the price is not more than 5% above the average of the middle
market quotations taken from the daily official list of the London Stock
Exchange for the five business days before the purchase date.

                                      104
<PAGE>

                             CERTAIN LEGAL MATTERS

   Certain legal matters relating to the ADSs will be passed upon by Cahill
Gordon & Reindel (a partnership including a professional corporation), New
York, New York, U.S. counsel for Shire. Certain U.K. legal matters, including
the validity of the ordinary shares, will be passed upon by Slaughter and May,
London, England, U.K. counsel for Shire. Milbank, Tweed, Hadley & McCloy LLP,
U.S. special counsel for Roberts, will deliver its opinion to Roberts
concerning the U.S. federal income tax consequences of the merger.

                                    EXPERTS

   Ernst & Young LLP, independent auditors, have audited Roberts' consolidated
financial statements and schedule included in its annual report on Form 10-K/A
for the year ended December 31, 1998, as set forth in their report, which is
incorporated by reference in this Prospectus-Proxy Statement and elsewhere in
the registration statement. Roberts' financial statements and schedule are
incorporated by reference in reliance on Ernst & Young LLP's report, given on
their authority as experts in accounting and auditing.

   The consolidated financial statements of Roberts Pharmaceutical Corporation
appearing in Roberts Pharmaceutical Corporation's Annual Report (Form 10-K) for
the years ended December 31, 1996 and December 31, 1997, have been audited by
PricewaterhouseCoopers LLP, independent accountants, as set forth in their
reports included in such financial statements and incorporated in this
Prospectus-Proxy Statement by reference. Such financial statements referred to
above are incorporated in this Prospectus-Proxy Statement by reference in
reliance upon such reports given on the authority of such firm as experts in
accounting and auditing.

   The consolidated financial statements of Shire for each of the years ended
June 30, 1996 and 1997, the six months ended December 31, 1997 and the year
ended December 31, 1998, appearing in Shire's Form 20-F for the year ended
December 31, 1998 and incorporated in this Prospectus-Proxy Statement by
reference, have been audited and reported upon by Arthur Andersen, independent
auditors. Such consolidated financial statements have been incorporated in this
Prospectus-Proxy Statement by reference in reliance upon the reports of Arthur
Andersen, and upon the authority of such firm as experts in auditing and
accounting.

   The financial statements of Richwood Pharmaceutical Company Inc. for the
years ended December 31, 1995 and 1996 incorporated in this Prospectus-Proxy
Statement by reference have been audited by Ernst & Young LLP, independent
auditors, as stated in their report in such financial statements, and are
incorporated by reference in this Prospectus-Proxy Statement in reliance upon
the report of such firm given their authority as experts in accounting and
auditing.

   The financial statements incorporated in this Prospectus-Proxy Statement by
reference to the Form 6-K dated August 26, 1999 of Pharmavene, Inc. for the
year ended December 31, 1996 and the period from February 16, 1990 (inception)
to December 31, 1996 have been so incorporated in reliance on the report of
PricewaterhouseCoopers LLP, independent accountants, given on the authority of
said firm as experts in accounting and auditing.


                                      105
<PAGE>

                                    PART II

                   INFORMATION NOT REQUIRED IN THE PROSPECTUS

Item 20. Indemnification Of Directors And Officers.

   Except as hereinafter set forth, there is no charter provision, by-law,
contract, arrangement or statute under which any director or officer of Shire
is insured or indemnified in any manner against any liability which he may
incur in his capacity as such.

   Pursuant to Paragraph 141 of the Articles of Association of Shire, every
person who was or is a director, alternate director or secretary of Shire shall
be indemnified out of the assets of Shire for all costs, charges, losses and
liabilities incurred in the proper execution of such person's duties or the
proper exercise of such person's powers, authorities and discretions.

   Under Section 310 of the Companies Act, Shire may not indemnify an officer
against any liability that by virtue of any rule of law would otherwise attach
to him in respect of any negligence, default, breach of duty or breach of trust
of which he may be guilty in relation to Shire, except that, under Section
310(3) of the Companies Act, Shire is not prevented, inter alia, (a) from
purchasing and maintaining for any such officer insurance against any such
liability, or (b) from indemnifying an officer against any liability incurred
by him in defending any proceedings (whether civil or criminal), in which
judgment is given in his favor or he is acquitted, or in connection with any
application in which relief is granted to him by the court in case of honest
and reasonable conduct.

   Shire maintains an insurance policy for its directors and officers in
respect of liabilities arising out of any act, error or omission while acting
in their capacities as directors or officers.

Item 21. Exhibits and Financial Statements.

 (a) Exhibits

                                 EXHIBIT INDEX

<TABLE>
<CAPTION>
 Exhibit No. Description
 ----------- -----------
 <C>         <S>
    2.1      Agreement and Plan of Merger by and among Shire Pharmaceuticals
             Group plc ("Shire"), Ruby Acquisition Sub Inc. and Roberts
             Pharmaceutical Corporation dated as of July 26, 1999 (attached as
             Annex A to the Prospectus-Proxy Statement included in this
             Registration Statement)
   *3.1      Memorandum and Articles of Association of Shire
   *4.1      Form of Deposit Agreement among Shire, Morgan Guaranty Trust
             Company of New York and Holders from time to time of Shire's ADSs
   *4.2      Form of Ordinary Share certificate
   *4.3      Form of ADR certificate (included within Exhibit 4.1)
 ***5.1      Opinion of Slaughter and May as to certain Shire related matters
 ***8.1      Opinion of Milbank, Tweed, Hadley & McCloy LLP regarding United
             States tax consequences of the merger
 *+10.1      Supply Agreement between Shire and Arenol Corporation dated
             January 1, 1996
 *+10.2      License Agreement between Shire and Nycomed Pharma AS dated
             January 14, 1987, as amended
  *10.3      License Agreement between Shire and Nycomed Pharma AS dated May
             25, 1992
 *+10.4      Agreement by and between Shire and Nycomed Pharma AS dated
             September 27, 1993
 *+10.5      Trademark License Agreement between Shire and Nycomed Pharma AS
             dated October 23, 1995
 *+10.6      License Agreement between Shire and Novartis Pharma A.G. dated as
             of August 31, 1995
</TABLE>

                                      II-1
<PAGE>

<TABLE>
<CAPTION>
 Exhibit No. Description
 ----------- -----------
 <C>         <S>
  *+10.7     Agreement between Shire and MacFarlan Smith Limited dated June 16,
             1997
  *+10.8     Extraction Agreement between Shire and MacFarlan Smith Limited
             dated June 16, 1997
  *+10.9     License Agreement between Shire and Johnson Matthey plc dated
             February 2, 1996
  *+10.10    License Agreement between Shire, Johnson Matthey plc and Anormed
             Inc. dated as of December 15, 1997
  *+10.11    License Agreement between Shire and Johnson Matthey plc dated
             December 15, 1997
  *+10.12    License Agreement between Shire and Synaptech Inc. dated November
             30, 1995
  *+10.13    Agreement between Shire and Janssen Pharmaceutica N.V. dated
             November 30, 1995
  *+10.14    Global Co-Development, Know-how and Supply Agreement between Shire
             and Janssen Pharmaceutica N.V. dated November 30, 1995
  *+10.15    Patent License Agreement between Shire and Ernir Snorrason dated
             March 31, 1992, as amended
  *+10.16    Pharmaceutical Formulation License Agreement between Shire and
             Hyal Pharmaceutical Corporation dated as of March 1, 1995
  *+10.17    Sale and Assignment Agreement between Athena Neurosciences, Inc.,
             Elan, SLI and Shire dated December 23, 1997
  *+10.18    Development and License Agreement between Shire and NeuroSearch
             A/S dated February 5, 1998
   *10.19    Agreement and Plan of Merger among Shire and Pharmavene, Inc.
             dated as of February 24, 1997
   *10.20    Agreement and Plan of Merger among Shire and Richwood
             Pharmaceutical Company, Inc. dated as of August 1, 1997
   *10.21    SHL Scheme
   *10.22    SPC Scheme
   *10.23    Executive Scheme
   *10.24    Sharesave Scheme
   *10.25    Employee Stock Purchase Plan
 ***10.26    Asset Purchase Agreement among Shire, Shire Supplies U.S. LLC,
             Arenol Corporation, Richard Vorisek and Robert Jaeder dated as of
             March 5, 1999
  ++10.27    Amendment Agreement to Global Co-Development, Know-How and Supply
             Agreement between Shire and Janssen Pharmaceutica N.V. dated July
             22, 1999
  **10.28    Option Agreement by and between Roberts Pharmaceutical Corporation
             and Shire dated as of July 26, 1999
 ***10.29    Share Purchase Agreement among Fuisz International Limited, Fuisz
             Technologies Ltd. and Shire Holdings Europe Limited dated October
             22, 1999.
    21.1     List of subsidiaries
    23.1     Consent of Arthur Andersen Chartered Accountants
    23.2     Consent of Ernst & Young LLP
    23.3     Consent of PricewaterhouseCoopers LLP
    23.4     Consent of Ernst & Young LLP
    23.5     Consent of PricewaterhouseCoopers LLP
 ***23.6     Consent of Slaughter and May (included in Exhibit 5.1)
 ***23.7     Consent of Milbank, Tweed, Hadley & McCloy LLP (included in
             Exhibit 8.1)
</TABLE>

                                      II-2
<PAGE>

<TABLE>
<CAPTION>
 Exhibit No. Description
 ----------- -----------
 <C>         <S>
    24.1     Power of Attorney as set forth on the signature page of this
             Registration Statement.
 ***99.1     Opinion of PaineWebber Incorporated (attached as Annex B to the
             Prospectus-Proxy Statement included in this Registration
             Statement)
 ***99.2     Opinion of Bear, Stearns & Co. Inc. (attached as Annex C to the
             Prospectus-Proxy Statement included in this Registration
             Statement)
    99.3     Consent of Ronald M. Nordmann
    99.4     Consent of Joseph E. Smith
    99.5     Consent of Zola P. Horovitz, Ph.D.
    99.6     Consent of John T. Spitznagel
 ***99.7     Consent of Robert A. Vukovich, Ph.D.
</TABLE>
- --------
*  Incorporated by reference to the exhibits to Shire's Registration Statement
   on Form F-1 (No. 333-8394).

** Incorporated by reference to Shire's Form 6-K filed on July 26, 1999.

***  To be filed by amendment.

+  Portions of this document, for which Shire has been granted confidential
   treatment, have been redacted and filed separately with the Securities and
   Exchange Commission.

++  Subject of a confidentiality treatment request. Certain portions have been
    omitted which have been filed separately with the Securities and Exchange
    Commission.

Item 22. Undertakings.

   A. The undersigned registrant hereby undertakes:

     1. To file, during any period in which offers or sales are being made, a
  post-effective amendment to this Registration Statement to include any
  material information with respect to the plan of distribution not
  previously disclosed in this Registration Statement or any material change
  to such information in this Registration Statement.

     2. That, for the purpose of determining any liability under the
  Securities Act of 1933, as amended (the "Securities Act"), each such post-
  effective amendment shall be deemed to be a new registration statement
  relating to the securities offered therein, and the offering of such
  securities at that time shall be deemed to be the initial bona fide
  offering thereof;

     3. To remove from registration by means of a post-effective amendment
  any of the securities being registered which remain unsold at the
  termination of the offering; and

     4. To file a post-effective amendment to this Registration Statement to
  include any financial statements required by Rule 3-19 of Regulation S-X at
  the start of any delayed offering or throughout a continuous offering.

     5. That, for purposes of determining any liability under the Securities
  Act, each filing of the registrant's annual report pursuant to Section
  13(a) or Section 15(d) of the Securities Exchange Act of 1934, as amended
  (and, where applicable, each filing of an employee benefit plan's annual
  report pursuant to Section 15(d) of the Securities Exchange Act of 1934),
  that is incorporated by reference in this Registration Statement shall be
  deemed to be a new registration statement relating to the securities
  offered therein, and the offering of such securities at that time shall be
  deemed to be the initial bona fide offering thereof.

     6. That, prior to any public reoffering of the securities registered
  hereunder through use of a prospectus which is a part of this Registration
  Statement, by any person or party who is deemed to be an

                                      II-3
<PAGE>

  underwriter within the meaning of Rule 145(c), the issuer undertakes that
  such reoffering prospectus will contain the information called for by the
  applicable registration form with respect to reofferings by persons who may
  be deemed underwriters, in addition to the information called for by the
  other items of the applicable form.

     7. That every prospectus (i) that is filed pursuant to paragraph (6)
  immediately preceding or (ii) that purports to meet the requirements of
  Section 10(a)(3) of the Securities Act and is used in connection with an
  offering of securities subject of Rule 415, will be filed as a part of an
  amendment to this Registration Statement and will not be used until such
  amendment is effective, and that, for purposes of determining any liability
  under the Securities Act, each such post-effective amendment shall be
  deemed to be a new registration statement relating to the securities
  offered therein, and the offering of such securities at that time shall be
  deemed to be the initial bona fide offering thereof.

     8. To (i) respond to requests for information that is incorporated by
  reference into the prospectus pursuant to items 4, 10(b), 11 or 13 of this
  Form, within one business day of receipt of such request, and to send the
  incorporated documents by first class mail or other equally prompt means;
  and (ii) arrange or provide for a facility in the U.S. for the purpose of
  responding to such requests. The undertaking in subparagraph (i) above
  includes information contained in documents filed subsequent to the
  effective date of the registration statement through the date of responding
  to the request.

     9. To supply by means of a post-effective amendment all information
  concerning a transaction and the company being acquired involved therein,
  that was not the subject of and included in the registration statement when
  it became effective.

   Insofar as indemnification for liabilities arising under the Securities Act
may be permitted to directors, officers and controlling persons of the
registrant pursuant to the provisions described under Item 20 above, or
otherwise, the registrant has been advised that in the opinion of the
Securities and Exchange Commission such indemnification is against public
policy as expressed in the Securities Act and is, therefore, unenforceable. In
the event that a claim for indemnification against such liabilities (other than
the payment by the registrant of expenses incurred or paid by a director,
officer or controlling person of the registrant in the successful defense of
any action, suit or proceeding) is asserted by such director, officer or
controlling person in connection with the securities being registered, the
registrant will, unless in the opinion of its counsel the matter has been
settled by controlling precedent, submit to a court of appropriate jurisdiction
the question of whether such indemnification by it is against public policy as
expressed in the Securities Act and will be governed by the final adjudication
of such issue.

                                      II-4
<PAGE>

                                   SIGNATURES

   Pursuant to the requirements of the Securities Act of 1933, as amended, the
Registrant has duly caused this Registration Statement to be signed on its
behalf by the undersigned, thereunto duly authorized, in the Town of Andover,
England, on,     , 1999.

                                          Shire Pharmaceuticals Group plc

                                                     /s/ Rolf Stahel
                                          By: _________________________________
                                                        Rolf Stahel
                                                      Chief Executive

                               POWER OF ATTORNEY

   KNOW ALL PERSONS BY THESE PRESENTS, that each person whose signature appears
below hereby constitutes and appoints Rolf Stahel, Stephen Stamp and Neil
Harris, and each of them acting individually, as his attorney-in-fact, each
with full power of substitution, for him in any and all capacities, to sign any
and all amendments to this Registration Statement (including post-effective
amendments), and to file the same, with exhibits thereto and other documents in
connection therewith, with the Securities and Exchange Commission, hereby
ratifying and confirming our signatures as they may be signed by our said
attorney to said Registration Statement and any and all amendments thereto.

   Pursuant to the requirements of the Securities Act of 1933, as amended, this
Registration Statement has been signed by the following persons in the
capacities and on the dates indicated:

<TABLE>
<CAPTION>
             Signature                           Title                    Date
             ---------                           -----                    ----

<S>                                  <C>                           <C>
          /s/ Rolf Stahel            Chief Executive
____________________________________  (Principal executive
            Rolf Stahel               officer)


   /s/ Dr. James Henry Cavanaugh     Non-executive Chairman
____________________________________
     Dr. James Henry Cavanaugh


     /s/ Stephen Anthony Stamp       Group Finance Director
____________________________________  (Principal financial
       Stephen Anthony Stamp          officer and principal
                                      accounting officer)


       /s/ Dr. Wilson Totten         Director
____________________________________
         Dr. Wilson Totten


      /s/ Dr. Barry John Price       Director
____________________________________
        Dr. Barry John Price


      /s/ Dr. Bernard Canavan        Director
____________________________________
        Dr. Bernard Canavan


     /s/ William Alfred Nuerge       Authorized Representative in
____________________________________  the U.S.
       William Alfred Nuerge
</TABLE>




                                      II-5
<PAGE>

                                 EXHIBIT INDEX

<TABLE>
<CAPTION>
 Exhibit No. Description
 ----------- -----------
 <C>         <S>
    2.1      Agreement and Plan of Merger by and among Shire Pharmaceuticals
             Group plc ("Shire"), Ruby Acquisition Sub Inc. and Roberts
             Pharmaceutical Corporation dated as of July 26, 1999 (attached as
             Annex A to the Prospectus-Proxy Statement included in this
             Registration Statement)
   *3.1      Memorandum and Articles of Association of Shire
   *4.1      Form of Deposit Agreement among Shire, Morgan Guaranty Trust
             Company of New York and Holders from time to time of Shire's ADSs
   *4.2      Form of Ordinary Share certificate
   *4.3      Form of ADR certificate (included within Exhibit 4.1)
 ***5.1      Opinion of Slaughter and May as to certain Shire related matters
 ***8.1      Opinion of Milbank, Tweed, Hadley & McCloy LLP regarding United
             States tax consequences of the merger
 *+10.1      Supply Agreement between Shire and Arenol Corporation dated
             January 1, 1996
 *+10.2      License Agreement between Shire and Nycomed Pharma AS dated
             January 14, 1987, as amended
  *10.3      License Agreement between Shire and Nycomed Pharma AS dated May
             25, 1992
 *+10.4      Agreement by and between Shire and Nycomed Pharma AS dated
             September 27, 1993
 *+10.5      Trademark License Agreement between Shire and Nycomed Pharma AS
             dated October 23, 1995
 *+10.6      License Agreement between Shire and Novartis Pharma A.G. dated as
             of August 31, 1995
 *+10.7      Agreement between Shire and MacFarlan Smith Limited dated June 16,
             1997
 *+10.8      Extraction Agreement between Shire and MacFarlan Smith Limited
             dated June 16, 1997
 *+10.9      License Agreement between Shire and Johnson Matthey plc dated
             February 2, 1996
 *+10.10     License Agreement between Shire, Johnson Matthey plc and Anormed
             Inc. dated as of December 15, 1997
 *+10.11     License Agreement between Shire and Johnson Matthey plc dated
             December 15, 1997
 *+10.12     License Agreement between Shire and Synaptech Inc. dated November
             30, 1995
 *+10.13     Agreement between Shire and Janssen Pharmaceutica N.V. dated
             November 30, 1995
 *+10.14     Global Co-Development, Know-how and Supply Agreement between Shire
             and Janssen Pharmaceutica N.V. dated November 30, 1995
 *+10.15     Patent License Agreement between Shire and Ernir Snorrason dated
             March 31, 1992, as amended
 *+10.16     Pharmaceutical Formulation License Agreement between Shire and
             Hyal Pharmaceutical Corporation dated as of March 1, 1995
 *+10.17     Sale and Assignment Agreement between Athena Neurosciences, Inc.,
             Elan, SLI and Shire dated December 23, 1997
 *+10.18     Development and License Agreement between Shire and NeuroSearch
             A/S dated February 5, 1998
  *10.19     Agreement and Plan of Merger among Shire and Pharmavene, Inc.
             dated as of February 24, 1997
  *10.20     Agreement and Plan of Merger among Shire and Richwood
             Pharmaceutical Company, Inc. dated as of August 1, 1997
  *10.21     SHL Scheme
  *10.22     SPC Scheme
  *10.23     Executive Scheme
  *10.24     Sharesave Scheme
</TABLE>

                                      II-6
<PAGE>

<TABLE>
<CAPTION>
 Exhibit No. Description
 ----------- -----------
 <C>         <S>
   *10.25    Employee Stock Purchase Plan
 ***10.26    Asset Purchase Agreement among Shire, Shire Supplies U.S. LLC,
             Arenol Corporation, Richard Vorisek and Robert Jaeder dated as of
             March 5, 1999
  ++10.27    Amendment Agreement to Global Co-Development, Know-How and Supply
             Agreement between Shire and Janssen Pharmaceutica N.V. dated July
             22, 1999
  **10.28    Option Agreement by and between Roberts Pharmaceutical Corporation
             and Shire dated as of July 26, 1999
 ***10.29    Share Purchase Agreement among Fuisz International Limited, Fuisz
             Technologies Ltd. and Shire Holdings Europe Limited dated October
             22, 1999.
    21.1     List of subsidiaries
    23.1     Consent of Arthur Andersen Chartered Accountants
    23.2     Consent of Ernst & Young LLP
    23.3     Consent of PricewaterhouseCoopers LLP
    23.4     Consent of Ernst & Young LLP
    23.5     Consent of PricewaterhouseCoopers LLP
 ***23.6     Consent of Slaughter and May (included in Exhibit 5.1)
 ***23.7     Consent of Milbank, Tweed, Hadley & McCloy LLP (included in
             Exhibit 8.1)
    24.1     Power of Attorney as set forth on the signature page of this
             Registration Statement.
 ***99.1     Opinion of PaineWebber Incorporated (attached as Annex B to the
             Prospectus-Proxy Statement included in this Registration
             Statement)
 ***99.2     Opinion of Bear, Stearns & Co. Inc. (attached as Annex C to the
             Prospectus-Proxy Statement included in this Registration
             Statement)
    99.3     Consent of Ronald M. Nordmann
    99.4     Consent of Joseph E. Smith
    99.5     Consent of Zola P. Horovitz, Ph.D.
    99.6     Consent of John T. Spitznagel
 ***99.7     Consent of Robert A. Vukovich, Ph.D.
</TABLE>
- --------
*  Incorporated by reference to the exhibits to Shire's Registration Statement
   on Form F-1 (No. 333-8394).

** Incorporated by reference to Shire's Form 6-K filed on July 26, 1999.

***  To be filed by amendment.

+  Portions of this document, for which Shire has been granted confidential
   treatment, have been redacted and filed separately with the Securities and
   Exchange Commission.

++  Subject of a confidentiality treatment request. Certain portions have been
    omitted which have been filed separately with the Securities and Exchange
    Commission.

                                      II-7

<PAGE>

                                                                     EXHIBIT 2.1
                              ___________________

                          AGREEMENT AND PLAN OF MERGER

                                     AMONG

                        SHIRE PHARMACEUTICALS GROUP plc,

                           RUBY ACQUISITION SUB INC.

                                      AND

                       ROBERTS PHARMACEUTICAL CORPORATION

                           DATED AS OF JULY 26, 1999

                              ___________________
<PAGE>

                               TABLE OF CONTENTS

                                                                       Page
                                                                       ----

                                   ARTICLE I


                                  DEFINITIONS

1.1.   Definitions.......................................................2

                                   ARTICLE II


                  THE MERGER; CONVERSION AND EXCHANGE OF STOCK

2.1.   Merger...........................................................10
2.2.   Effective Time...................................................10
2.3.   Effects of the Merger............................................11
2.4.   Further Assurances...............................................11
2.5.   Merger Consideration.............................................11
2.6.   Exchange Provisions..............................................13
2.7.   Consideration for Ordinary Shares................................15
2.8.   Tax-Free Reorganization..........................................15

                                  ARTICLE III


                         REPRESENTATIONS AND WARRANTIES

3.1.   Representations and Warranties of Roberts........................15
       (a)   Organization; Standing and Power...........................16
       (b)   Subsidiaries and Investments...............................16
       (c)   Capitalization.............................................17
       (d)   Authority..................................................18
       (e)   Noncontravention...........................................18
       (f)   Government Approval; Consents..............................18
       (g)   SEC Documents..............................................19
       (h)   Information Supplied.......................................19
       (i)   Absence of Certain Changes or Events.......................20
       (j)   Compliance with Law........................................21
       (k)   Affiliate Arrangements.....................................21
       (l)   Transaction Fees...........................................21
       (m)   Litigation.................................................22
       (n)   Taxes and Tax Returns......................................22
       (o)   Real Property..............................................23
       (p)   Licenses, Permits and Authorizations.......................24
       (q)   ERISA and Employee Matters.................................24
       (r)   Labor Relations............................................26
       (s)   Intellectual Property Rights...............................27
       (t)   Insurance..................................................28

                                      -i-
<PAGE>

                                                                       Page
                                                                       ----

       (u)   Books and Records..........................................28
       (v)   Undisclosed Liabilities....................................29
       (w)   FDA, DEA Matters...........................................29
       (x)   Environmental Matters......................................31
       (y)   Products...................................................33
       (z)   Marketing Practices........................................34
       (aa)  Affiliates.................................................34
       (bb)  Pooling....................................................34
       (cc)  Business Combination.......................................34
3.2.   Representations and Warranties of Shire..........................34
       (a)   Organization; Standing and Power...........................35
       (b)   Subsidiaries and Investments...............................35
       (c)   Capitalization.............................................36
       (d)   Authority..................................................36
       (e)   Noncontravention...........................................37
       (f)   Government Approval; Consents..............................37
       (g)   Reports and Financial Statements...........................38
       (h)   Information Supplied.......................................38
       (i)   Absence of Certain Changes or Events.......................39
       (j)   Compliance with Law........................................40
       (k)   Affiliate Arrangements.....................................40
       (l)   Transaction Fees...........................................40
       (m)   Litigation.................................................41
       (n)   Taxes and Tax Returns......................................41
       (o)   Real Property..............................................42
       (p)   Licenses, Permits and Authorizations.......................42
       (q)   ERISA and Employee Matters.................................43
       (r)   Labor Relations............................................45
       (s)   Intellectual Property Rights...............................45
       (t)   Insurance..................................................46
       (u)   Books and Records..........................................46
       (v)   Undisclosed Liabilities....................................47
       (w)   FDA, DEA Matters...........................................47
       (x)   Environmental Matters......................................49
       (y)   Products...................................................51
       (z)   Marketing Practices........................................52
       (aa)  Ordinary Shares............................................52
       (bb)  Pooling....................................................52
       (cc)  Merger Consideration.......................................52
       (dd)  Active Trade or Business...................................53
       (ee)  Asset Acquisitions.........................................53
       (ff)  Ownership of Roberts Shares................................53

                                   ARTICLE IV


                              COVENANTS OF ROBERTS

4.1.   Regular Course of Business.......................................54

                                      -ii-
<PAGE>

                                                                       Page
                                                                       ----

4.2.   Certain Prohibited Activities....................................54
4.3.   Notice of Certain Events.........................................55
4.4.   Access...........................................................56
4.5.   Approvals........................................................56
4.6.   No Solicitation..................................................56
4.7.   Pooling of Interests.............................................57
4.8.   ISRA.............................................................58




                                   ARTICLE V


                     COVENANTS OF SHIRE AND ACQUISITION SUB

5.1.   Regular Course of Business.......................................58
5.2.   Certain Prohibited Activities....................................58
5.3.   Notice of Certain Events.........................................59
5.4.   Access...........................................................60
5.5.   Approvals........................................................60
5.6.   No Solicitation..................................................60
5.7.   Pooling of Interests.............................................61
5.8.   Indemnification..................................................62


                                   ARTICLE VI


                          AGREEMENTS REGARDING OPTIONS

                               AND OTHER BENEFITS

6.1.  Stock Option Plans................................................63
6.2.  Continuation of Benefits..........................................64
6.3.  Severance Policy and Other Agreements.............................64
6.4.  1999 Bonus........................................................64
6.5.  Waiver of Preexisting Conditions; Credit for
           Deductibles; Service Credit..................................65

                                  ARTICLE VII


                              CONDITIONS PRECEDENT

7.1.   Conditions to the Obligations of Each Party to Effect the Merger.65
       (a)   Shareholder Approvals......................................65
       (b)   Certain Approvals..........................................65
       (c)   No Proceeding or Litigation................................65
       (d)   Securities Laws............................................66
7.2.   Additional Conditions to the Obligations of Roberts..............66
       (a)   Agreements.................................................66
       (b)   Representations and Warranties.............................66
       (c)   Officer's Certificate......................................66

                                     -iii-
<PAGE>

                                                                       Page
                                                                       ----

       (d)   Consents from Third Parties................................66
       (e)   Listing....................................................66
       (f)   Tax Opinions...............................................67
       (g)   Pooling Letter.............................................67
       (h)   Nasdaq.....................................................67
7.3.   Additional Conditions to the Obligations of
          Shire and Acquisition Sub.....................................67
       (a)   Agreements.................................................68
       (b)   Representations and Warranties.............................68
       (c)   Roberts Officer's Certificate..............................68
       (d)   Pooling Letter.............................................68

                                  ARTICLE VIII


                                OTHER AGREEMENTS

8.1.   Preparation of Form F-4, Form F-6, the Proxy Statement and the UK
         Disclosure Document............................................68
8.2.   Roberts Shareholders Meeting.....................................69
8.3.   Shire Shareholders Meeting.......................................69
8.4.   Acquisition Sub Actions..........................................70

                                   ARTICLE IX


                       TERMINATION, AMENDMENT AND WAIVER

9.1.   Termination......................................................70
9.2.   Effect of Termination............................................72
9.3.   Amendment........................................................74
9.4.   Waiver...........................................................74

                                   ARTICLE X


                               GENERAL PROVISIONS

10.1.  Public Statements................................................75
10.2.  Notices..........................................................75
10.3.  Interpretation...................................................76
10.4.  Counterparts.....................................................76
10.5.  Entire Agreement.................................................76
10.6.  Governing Law....................................................77
10.7.  Validity.........................................................77
10.8.  Assignment.......................................................77
10.9.  Expenses.........................................................77
10.10. Enforcement......................................................77

                                      -iv-
<PAGE>

EXHIBITS

Exhibit 1    Option Agreement
Exhibit 2-A  Shareholder Agreement - Roberts Shareholders
Exhibit 2-B  Shareholder Agreement - Shire Shareholders
Exhibit 3    Section 145 Letter

SCHEDULES

Schedule 1      Entities Required to Execute the Shareholder Agreement
Schedule 2      Knowledge Officers
Schedule 3      Officers and Directors of Surviving Corporation

                                      -v-
<PAGE>

                          AGREEMENT AND PLAN OF MERGER

          AGREEMENT AND PLAN OF MERGER (this "Agreement"), dated as of July 26,
                                              ---------
1999, among Shire Pharmaceuticals Group plc, a public limited company organized
under the laws of England and Wales ("Shire"), Ruby Acquisition Sub Inc., a New
                                      -----
Jersey corporation ("Acquisition Sub") and a direct wholly owned Subsidiary of
                     ---------------
Shire, and Roberts Pharmaceutical Corporation, a New Jersey corporation

("Roberts").
- ---------

          WHEREAS, the parties hereto desire to consummate a merger (the

"Merger") whereby Acquisition Sub will be merged with and into Roberts and
 ------
Roberts will be the surviving corporation in the Merger, all upon the terms and
conditions set forth herein and in accordance with the New Jersey Business
Corporation Act ("New Jersey Law");
                  --------------

          WHEREAS, the respective Boards of Directors (or a duly authorized
committee thereof) of each of Shire, Acquisition Sub and Roberts have approved
this Agreement, the Merger and the other transactions contemplated hereby;

          WHEREAS, the Merger is intended to be treated as a tax-free
reorganization pursuant to the provisions of Section 368(a)(1)(A) and Section
368(a)(2)(E) of the Internal Revenue Code of 1986, as amended (the "Code");
                                                                    ----

          WHEREAS, concurrently with the execution of this Agreement and as a
condition and inducement to Shire and Acquisition Sub to enter into this
Agreement Roberts has granted to Shire an irrevocable option to acquire
authorized but unissued shares of common stock, par value $.01 per share of
Roberts (the "Common Stock") representing 19.9% of the outstanding shares of
Common Stock as provided in an Option Agreement in the form attached hereto as
Exhibit 1; and

          WHEREAS, concurrently with the execution of this Agreement and as a
condition and inducement to the parties to enter into this Agreement, the
persons listed on Schedule 1-A hereto have committed to vote in favor of
approving this Agreement as provided in a Shareholder Agreement in the form
attached hereto as Exhibit 2-A and the entity listed on Schedule 1-B hereto has
committed to vote in favor of approving this Agreement as provided in a
Shareholder Agreement in the form attached hereto as Exhibit 2-B.
<PAGE>

                                      -2-


          NOW, THEREFORE, in consideration of the premises and the
representations, warranties and agreements herein contained, the parties hereby
agree as follows:

                                   ARTICLE I


                                  DEFINITIONS

          1.1.  Definitions.  For all purposes of this Agreement, except as
                -----------
otherwise expressly provided or unless the context otherwise requires, the terms
defined in this Article have the meanings assigned to them in this Article:

          "Acquisition Sub" has the meaning set forth in the preamble hereto.
           ---------------

          "Agreement" has the meaning set forth in the preamble hereto.
           ---------

          "Business Day" means a day other than a Saturday, a Sunday or a day on
           ------------
     which banks in New York, New York or London, England are permitted or
     required by law to close.

          "Cash Equivalents" means (a) cash, (b) marketable direct obligations
           ----------------
     issued by the United States government or any agency thereof and backed by
     the full faith and credit of the United States, in each case maturing
     within three months from the date of acquisition thereof, and (c)
     investments in money market funds which invest substantially all of their
     assets in assets of the types described in clauses (a) and (b) of this
     definition.

          "CERCLA" has the meaning set forth in Section 3.1(x)(v).
           ------

          "Certificate of Merger" has the meaning set forth in Section 2.2.
           ---------------------

          "Closing" has the meaning set forth in Section 2.2.
           -------

          "Closing Date" has the meaning set forth in Section 2.2.
           ------------

          "Code" has the meaning set forth in the preamble hereto.
           ----

          "Common Stock" has the meaning set forth in the preamble hereto.
           ------------
<PAGE>

                                      -3-

          "Constituent Corporations" has the meaning set forth in Section 2.1.
           ------------------------

          "DEA" has the meaning set forth in Section 3.1(w).
           ---

          "Depositary" has the meaning set forth in Section 2.5(f).
           ----------

          "DOJ" has the meaning set forth in Section 3.1(w)
           ---

          "Effective Time" has the meaning set forth in Section 2.2.
           --------------

          "Employment Obligations" has the meaning set forth in Section 3.1(q).
           ----------------------

          "Environmental Law" means CERCLA, the Resource Conservation and
           -----------------
     Recovery Act of 1976, as amended, the New Jersey Industrial Site Recovery
     Act ("ISRA"), the Illinois Responsible Property Transfer Act ("RPTA"), the
           ----                                                     ----
     Toxic Substances Control Act, as amended, and any other applicable federal,
     state, local or foreign statute, rule, regulation, order, judgment,
     directive, decree or the common law regulating, relating to, or imposing
     liability or standards of conduct concerning air emissions, water
     discharges, noise emissions, or exposure to or the release or threatened
     release or discharge of any Hazardous Material into the environment, the
     generation, handling, use, treatment, storage, transport, disposal or
     remediation of any Hazardous Material, or otherwise concerning pollution or
     the protection of the outdoor or indoor environment, (including, without
     limitation, ambient or indoor air, surface water, groundwater, soil,
     subsurface strata and natural resources, including, without limitation,
     wetlands, flora and fauna, or public or employee health or safety, or the
     experimental use of animals or disposal of animal carcasses).

          "Environmental Permit" means any permit, license, approval, consent or
           --------------------
     other authorization by a federal, state, local or non-U.S. government or
     regulatory entity pursuant to any Environmental Law.

          "Equity Equivalent" has the meaning set forth in Section 3.1(c).
           -----------------
<PAGE>

                                      -4-

          "ERISA" has the meaning set forth in Section 3.1(q).
           -----

          "Exchange Act" means the U.S. Securities Exchange Act of 1934, as
           ------------
     amended.

          "Exchange Agent" has the meaning set forth in Section 2.6(b).
           --------------

          "Exchange Ratio" has the meaning set forth in Section 2.5(a).
           --------------

          "FDA" has the meaning set forth in Section 3.1(w).
           ---

          "Filed SEC Documents" has the meaning set forth in Section 3.1(i).
           -------------------

          "Form F-4" has the meaning set forth in Section 3.1(h).
           --------

          "Form F-6" has the meaning set forth in Section 8.1.
           --------

          "FSA" means The Financial Services Act 1986 of the United Kingdom.
           ---

          "Hazardous Material" means any pollutant, contaminant, or hazardous,
           ------------------
     toxic, medical, biohazardous, infectious or dangerous waste, substance,
     constituent or material, any asbestos, any petroleum, oil (including crude
     oil or any fraction thereof), any radioactive substance, animal carcass,
     any toxin, chemical, virus, infectious disease or disease-causing agent, or
     any other substance, waste, constituent, chemical or material that can give
     rise to liability under any Environmental Law.

          "Holders" means the holders of record of certificates of Common Stock
           -------
     as of the Effective Time.

          "Indebtedness" means with respect to any entity (a) all obligations
           ------------
     for borrowed money, (b) all obligations evidenced by bonds, debentures,
     notes or other similar instruments, (c) all obligations for the
     reimbursement of any obligor on any letter of credit, banker's acceptance
     or similar credit transaction, (d) all obligations secured by a Lien on
     property or assets of such entity, (e) financing leases which would be
     treated as debt under either US GAAP or UK GAAP and (f) guarantees and
     other contingent obligations in respect of Indebtedness referred to in
     clauses (a) through (e) above.
<PAGE>

                                      -5-

          "Intellectual Property" has the meaning set forth in Section
           ---------------------
     3.1(s)(i).

          "knowledge" will be deemed to be present as to Roberts when the matter
           ---------
     in question was actually known by an officer of Roberts identified on

     Schedule 2-A attached hereto and will be deemed to be present as to Shire
     ------------
     when the matter in question was actually known by an officer of Shire
     identified on Schedule 2-B attached hereto.
                   ------------

          "Lien" means any lien, claim, pledge, assignment, hypothecation,
           ----
     conditional sale, retention of title, mortgage, deed of trust, pledge,
     security interest, charge or encumbrance of any kind other than a
     mechanic's, warehousemen's or similar statutory lien or any agreement to
     provide any of the foregoing.

          "LSE" means The London Stock Exchange.
           ---

          "MCA" has the meaning set forth in Section 3.1(w).
           ---

          "Merger" has the meaning set forth in the preamble hereto.
           ------

          "Merger Consideration" has the meaning set forth in Section 2.5(a).
           --------------------

          "New Jersey Law" has the meaning set forth in the preamble hereto.
           --------------

          "Option" means a right and option to purchase one share of Common
           ------
     Stock which was granted pursuant to either of the Roberts Option Plans.

          "Optionee" has the meaning set forth in Section 6.1.
           --------

          "Ordinary Shares" means validly issued, fully paid and nonassessable
           ---------------
     ordinary shares, with a nominal value of U.K. five pence each, of Shire.

          "Permits" means all approvals, authorizations, qualifications,
           -------
     consents, licenses, franchises, orders and other permits of all
     governmental or regulatory agencies or bodies, whether federal, state,
     local or non-U.S.

          "Permitted Lien" means (i) any Lien for Taxes not yet due or
           --------------
     delinquent or being contested in good faith by appropriate proceedings for
     which adequate reserves have
<PAGE>

                                      -6-

     been established in accordance with US GAAP or UK GAAP, as the case may be,
     (ii) any statutory Lien arising in the ordinary course of business by
     operation of law with respect to a liability that is not yet due or
     delinquent and (iii) any minor imperfection of title or similar Lien which
     individually or in the aggregate with other such Liens does not materially
     impair the value of the property subject to such Lien or the use of such
     property in the conduct of the business of Roberts or Shire, as the case
     may be, or any of its Subsidiaries.

          "Proxy Statement" means a proxy statement relating to the approval by
           ---------------
     the shareholders of Roberts of this Agreement (as amended or supplemented
     from time to time).

          "Public UK Documents" has the meaning set forth in Section 3.2(i).
           -------------------

          "Rights" means the Rights issued pursuant to the Rights Agreement.
           ------

          "Rights Agreement" means the Rights Agreement, dated as of December
           ----------------
     16, 1996, between Roberts and Continental Stock Transfer and Trust Company,
     as amended through the date hereof.

          "Roberts" has the meaning set forth in the preamble hereto.
           -------

          "Roberts Acquisition Transaction" has the meaning set forth in Section
           -------------------------------
     4.6(a).

          "Roberts Disclosure Schedule" has the meaning set forth in Section
           ---------------------------
     3.1.

          "Roberts Governmental Approvals" has the meaning set forth in Section
           ------------------------------
     3.1(f).

          "Roberts Insurance Policies" has the meaning set forth in Section
           --------------------------
     3.1(t).

          "Roberts Intellectual Property" has the meaning set forth in Section
           -----------------------------
     3.1(s)(i).

          "Roberts Material Adverse Effect" means any condition, change or
           -------------------------------
     effect that is materially adverse to the business, results of operations or
     financial condition of Roberts and its Subsidiaries taken as a whole, but
<PAGE>

                                      -7-

     excluding conditions, changes or effects that (a) are caused by general
     economic conditions or conditions affecting the pharmaceutical industry as
     a whole, whether in the United States or internationally, which conditions
     do not affect Roberts and its Subsidiaries in a disproportional manner or
     (b) are related to or result from any action or inaction on the part of
     Shire or any of its affiliates.

          "Roberts Option Plans" means Roberts' Incentive Stock Option Plan,
           --------------------
     Equity Incentive Plan, Restricted Stock Option Plan and Employee Stock
     Purchase Plan.

          "Roberts Product Sites" has the meaning set forth in Section
           ---------------------
     3.1(x)(v).

          "Roberts Shareholder Approval" has the meaning set forth in Section
           ----------------------------
     3.1(d).

          "Roberts Shareholders Meeting" has the meaning set forth in Section
           ----------------------------
     8.2.

          "Roberts Superior Proposal" has the meaning set forth in Section
           -------------------------
     4.6(b).

          "Roberts Third Party Approvals" has the meaning set forth in Section
           -----------------------------
     3.1(f).

          "Roberts Third Party Site" has the meaning set forth in Section
           ------------------------
     3.1(x)(vi)."SARs" has the meaning set forth in Section 3.1(c).
                 ----

          "SEC" means the Securities and Exchange Commission.
           ---

          "SEC Documents" has the meaning set forth in Section 3.1(g).
           -------------

          "Securities Act" means the U.S. Securities Act of 1933, as amended.
           --------------

          "Shareholder Protection Act" means Chapter 10A of the New Jersey Law.
           --------------------------

          "Shire" has the meaning set forth in the preamble hereto.
           -----

          "Shire Acquisition Transaction" has meaning set forth in Section 5.6.
           -----------------------------
<PAGE>

                                      -8-

          "Shire ADRs" means the American Depositary Receipts representing the
           ----------
     Shire ADSs issued pursuant to a Deposit Agreement, dated as of April 1,
     1998, between Shire and the Depositary.

          "Shire ADSs" means American Depositary Shares, each representing three
           ----------
     Ordinary Shares, of Shire.

          "Shire Disclosure Schedule" has the meaning set forth in Section 3.2.
           -------------------------

          "Shire Governmental Approvals" has the meaning set forth in Section
           ----------------------------
     3.2(f).

          "Shire Insurance Policies" has the meaning set forth in Section
           ------------------------
     3.2(t).

          "Shire Intellectual Property" has the meaning set forth in Section
           ---------------------------
     3.2(s)(i).

          "Shire Material Adverse Effect" means any condition, change or effect
           -----------------------------
     that is materially adverse to the business, results of operations or
     financial condition of Shire and its Subsidiaries taken as a whole, but
     excluding conditions, changes or effects that (a) are caused by general
     economic conditions or conditions affecting the pharmaceutical industry as
     a whole, whether in the United Kingdom or internationally, which conditions
     do not affect Shire and its Subsidiaries in a disproportionate manner or
     (b) are related to or result from any action or inaction on the part of
     Roberts or any of its affiliates.

          "Shire Option Plans" means Shire's SHL Scheme, SPC Scheme, Executive
           ------------------
     Scheme (Part A and Part B), Sharesave Scheme, Employee Stock Purchase Plan,
     Pharmavene Stock Option Plan and Richwood Stock Option Plan, collectively.

          "Shire Product Sites" has the meaning set forth in Section 3.2(x)(v).
           -------------------

          "Shire Share Value" means one-third of the average of the last
           -----------------
     reported sale price per Shire ADR on the Nasdaq National Market over the
     fifteen consecutive trading days ending on the third trading day
     immediately preceding the Closing Date.

          "Shire Shareholder Approval" has the meaning set forth in Section
           --------------------------
     3.2(d).
<PAGE>

                                      -9-

          "Shire Shareholders Meeting" has the meaning set forth in Section 8.3.
           --------------------------

          "Shire Superior Proposal" has the meaning set forth in Section 5.6(b).
           -----------------------

          "Shire Third Party Approvals" has the meaning set forth in Section
           ---------------------------
     3.2(f).

          "Shire Third Party Site" has the meaning set forth in Section
           ----------------------
     3.2(x)(vi).

          "Subsidiary" of any person means (i) any corporation of which the
           ----------
     outstanding capital stock having at least a majority of the votes entitled
     to be cast in the election of directors under ordinary circumstances shall
     at the time be owned, directly or indirectly, by such person or (ii) any
     other person of which at least a majority of the voting interest under
     ordinary circumstances is at the time, directly or indirectly, owned by
     such person.

          "Surviving Corporation" has the meaning set forth in Section 2.1.
           ---------------------

          "Tax" or "Taxes" means (i) all federal, state, local or non-U.S.
           ---      -----
     taxes, charges, fees, imposts, levies or other assessments, including,
     without limitation, all net income, alternative minimum, gross receipts,
     capital, sales, use, ad valorem, value added, transfer, franchise, profits,
     inventory, capital stock, license, withholding, payroll, employment, social
     security, unemployment, excise, severance, stamp, occupation, property and
     estimated taxes, customs duties, fees, assessments and charges of any kind
     whatsoever, (ii) all interest, penalties, fines, additions to tax or other
     additional amounts imposed by any taxing authority in connection with any
     item described in clause (i) and (iii) all transferee, successor, several
     or contractual liability in respect of any items described in clause (i) or
     (ii).

          "Tax Returns" means all returns, declarations, reports, estimates,
           -----------
     information returns and statements required to be filed in respect of any
     Taxes.

          "UK Disclosure Documents" means the documentation necessary for the
           -----------------------
     implementation of this Agreement including a circular to Shire's
     shareholders containing (i) a notice convening an extraordinary general
     meeting of Shire
<PAGE>

                                      -10-

     at which a resolution will be proposed to approve the allotment of share
     capital necessary to give effect to this Agreement, and (ii) such other
     information as required by applicable law, together with a U.K. prospectus
     and forms of proxy.

          "UK GAAP" has the meaning set forth in Section 3.2(g).
           -------

          "UK Prospectus" means a prospectus prepared in accordance with the FSA
           -------------
     with respect to the Ordinary Shares.

          "US GAAP" has the meaning set forth in Section 3.1(g).
           -------

                                   ARTICLE II


                  THE MERGER; CONVERSION AND EXCHANGE OF STOCK

          2.1.  Merger.  At the Effective Time, in accordance with and subject
                ------
to the terms and conditions of this Agreement and New Jersey Law, Acquisition
Sub shall be merged with and into Roberts and Roberts shall continue its
corporate existence under New Jersey Law as the surviving corporation
(Acquisition Sub and Roberts are sometimes referred to herein collectively as
the "Constituent Corporations," and Roberts, as the surviving corporation in the
     ------------------------
Merger, is sometimes referred to herein as the "Surviving Corporation").
                                                ---------------------

          2.2.  Effective Time.  Subject to the provisions of this Agreement,
                --------------
the parties agree to cause to be duly executed a Certificate of Merger (the

"Certificate of Merger"), which shall be duly delivered to the Secretary of
- ----------------------
State for the State of New Jersey for filing as provided by New Jersey Law.  The
Merger shall become effective upon the filing of the Certificate of Merger with
the Secretary of State for the State of New Jersey (the "Effective Time").
                                                         --------------
Prior to such filings of the Certificate of Merger, a closing (the "Closing")
                                                                    -------
will be held at the offices of Cahill Gordon & Reindel, 80 Pine Street, New
York, New York 10005, which shall be on the second Business Day after the
satisfaction or waiver of the conditions set forth in Article VII hereof, unless
another time, date or place is agreed by the parties hereto or unless this
Agreement has been terminated in accordance with its terms.  The date of the
Closing shall be referred to herein as the "Closing Date."  The
                                            ------------
<PAGE>

                                      -11-

parties agree that the Effective Time shall occur on the Closing Date.

          2.3.  Effects of the Merger.  At the Effective Time, (a) the effects
                ---------------------
of the Merger shall be as provided under all applicable provisions of New Jersey
Law, (b) the Certificate of Incorporation of Roberts as in effect immediately
prior to the Effective Time shall be the Certificate of Incorporation of the
Surviving Corporation until thereafter amended as provided therein and in
accordance with New Jersey Law, (c) the By-Laws of Roberts as in effect
immediately prior to the Effective Time shall be the By-Laws of the Surviving
Corporation until thereafter amended as provided therein and in accordance with
New Jersey Law, (d) the individuals listed on Schedule 3-A shall be the officers
                                              ------------
of the Surviving Corporation until the earlier of their resignation or removal
or until their successors have been duly elected and qualified in accordance
with the Certificate of Incorporation and By-Laws of the Surviving Corporation,
and (e) the individuals listed on Schedule 3-B shall be the directors of the
                                  ------------
Surviving Corporation until the earlier of their resignation or removal or until
their successors have been duly elected and qualified in accordance with the
Certificate of Incorporation and By-Laws of the Surviving Corporation.

          2.4.  Further Assurances.  If, at any time after the Effective Time,
                ------------------
the Surviving Corporation shall consider or be advised that any deeds, bills of
sale, assignments, assurances or any other actions or things are necessary or
desirable to vest, perfect or confirm of record or otherwise in the Surviving
Corporation its right, obligation, title or interest in, to or under any of the
rights, properties or assets of either of the Constituent Corporations as a
result of, or in connection with, the Merger or otherwise to carry out this
Agreement, the officers and directors of the Surviving Corporation shall be
authorized to execute and deliver, in the name and on behalf of each of the
Constituent Corporations or otherwise, all such deeds, bills of sale,
assignments and assurances and to take and do, in the name and on behalf of each
of the Constituent Corporations or otherwise, all such other actions and things
as may be necessary or desirable to vest, perfect or confirm any and all right,
obligation, title and interest in, to and under such rights, properties or
assets in the Surviving Corporation or otherwise to carry out this Agreement so
long as such actions and things are consistent with the terms of this Agreement
and the Certificate of Merger.

          2.5.  Merger Consideration.  (a)  At the Effective Time, by virtue
                --------------------
of the Merger and without any action on the
<PAGE>

                                      -12-

part of the Holders, each issued and outstanding share of Common Stock (other
than shares canceled in accordance with Section 2.5(d)) together with the
associated Right shall be converted into the right to receive from Shire a
number of Ordinary Shares (the "Merger Consideration") determined as set forth
                                --------------------
below (the "Exchange Ratio"):
            --------------

             (i) If the Shire Share Value is equal to or greater than $7.91 and
     equal to or less than $9.67, the Exchange Ratio shall be 3.4122;

             (ii) If the Shire Share Value is equal to or greater than $7.03 and
     less than $7.91, the Exchange Ratio shall be determined by dividing $27.00
     by the Shire Share Value;

             (iii)  If the Shire Share Value is less than $7.03, the Exchange
     Ratio shall be 3.8407;

             (iv) If the Shire Share Value is greater than $9.67 and less than
     or equal to $10.55, the Exchange Ratio shall be determined by dividing
     $33.00 by the Shire Share Value; and

             (v) If the Shire Share Value is greater than $10.55, the Exchange
     Ratio shall be 3.1280.

          (b)  Each issued and outstanding share of capital stock of Acquisition
Sub shall be canceled.

          (c)  In consideration of the cancellation of shares of capital stock
of Acquisition Sub pursuant to Section 2.5(b) and the issuance of Ordinary
Shares pursuant to Section 2.5(a), the Surviving Corporation shall issue one
fully paid and nonassessable share of its common stock, par value $.01 per
share, to Shire for each share canceled pursuant to Section 2.5(b).

          (d)  Each share of Common Stock (and associated Rights) that is owned
by Roberts or any Subsidiary of Roberts, or Shire or any Subsidiary of Shire,
shall automatically be canceled and retired and shall cease to exist, and no
Ordinary Shares or other consideration shall be delivered in exchange therefor.

          (e)  The parties acknowledge that listing of the Ordinary Shares
comprising the Merger Consideration on the London Stock Exchange will not be
permitted unless and until this Agreement is unconditional in all respects,
including the filings of the Certificate of Merger having taken place as
<PAGE>

                                      -13-

provided for in Section 2.2.  The parties therefore agree that, without
prejudice to Articles VII, VIII and IX of this Agreement, once the Ordinary
Shares have been allotted, they shall use their respective best efforts to
procure that filings of the Certificate of Merger takes place immediately before
9:30 a.m. (New York time) on the Closing Date, and that the Ordinary Shares to
be issued pursuant to this Agreement are admitted to the Official List of the
London Stock Exchange at 2:30 p.m. (London time).

          (f)  Notwithstanding Section 2.5(a), unless the Holders otherwise
elect, Shire will provide Holders with one-third of a Shire ADS (represented by
Shire ADRs) for each Ordinary Share such Holder would be entitled to receive
pursuant to Section 2.5(a).  Holders must irrevocably elect to receive all or
any portion of their Ordinary Shares as Ordinary Shares in lieu of such Shire
ADSs at the time they surrender their certificates representing shares of Common
Stock in accordance with the provisions described in Section 2.6.  The receipt
of Shire ADSs will be deemed for all purposes of this Agreement as the receipt
of the underlying Ordinary Shares and such Shire ADSs will be deemed for all
purposes of this Agreement to constitute Merger Consideration.  Shire will pay
all fees and expenses associated with the issuance of the Ordinary Shares
constituting Shire ADSs to Morgan Guaranty Trust Company of New York, as
depositary (the "Depositary"), for the issuance by the Depositary of the
                 ----------
associated Shire ADRs.

          (g)  Shire shall not be required to pay any fractional Ordinary Shares
or Shire ADSs pursuant to this Section 2.5.  In lieu of receiving a fractional
Ordinary Share or Shire ADS, each Holder otherwise entitled to (i) a fractional
Ordinary Share shall receive cash (without interest) in an amount equal to (a)
the latest closing mid-market price of the Ordinary Shares on the London Stock
Exchange on the day immediately following the Closing Date divided by (b) the
fractional interest of an Ordinary Share that would otherwise be payable and
(ii) a fractional Shire ADS shall receive cash (without interest) in an amount
equal to (a) the last reported sale price of Shire ADRs on the Nasdaq National
Market for the day immediately following the Closing Date divided by (b) the
fractional interest of a Shire ADS that would otherwise be payable.

          2.6.  Exchange Provisions.  (a)  At the Effective Time, all shares
                -------------------
of Common Stock (and associated Rights), by virtue of the Merger and without any
action on the part of the Holders, shall no longer be outstanding and shall be
canceled and retired and shall cease to exist, and each Holder of a certificate
<PAGE>

                                      -14-

representing any such share of Common Stock shall thereafter cease to have any
rights with respect to such share of Common Stock (and associated Right) except
the right to receive the Merger Consideration for such share of Common Stock
(and associated Right) specified in Section 2.5.

          (b)  Prior to the Effective Time, Shire shall designate a bank or
trust company reasonably satisfactory to Roberts to act as Exchange Agent
hereunder (the "Exchange Agent").  At the Effective Time, Shire shall (i) issue
                --------------
to and deposit with the Depositary, for the benefit of the holders of shares of
Common Stock converted into Shire ADSs in accordance with Sections 2.5(a) and
(f), Ordinary Shares in an amount sufficient to permit the Depositary to issue
Shire ADSs representing the number of Shire ADSs issuable pursuant to Sections
2.5(a) and (f) and (ii) deposit, in trust, with the Exchange Agent for the
benefit of the Holders, Ordinary Shares constituting the Merger Consideration.
As soon as practicable after the Effective Time, the Surviving Corporation shall
cause the Exchange Agent to mail to each Holder (i) a form of letter of
transmittal specifying that delivery shall be effected, and risk of loss and
title to certificates of Common Stock shall pass, only upon proper delivery of
such certificates to the Exchange Agent and (ii) instructions for use in
surrendering such certificates in exchange for the Merger Consideration set
forth in Section 2.5.  Such letter of transmittal shall also indicate that
Holders have an irrevocable right to elect to receive all or any portion of
their Ordinary Shares as Ordinary Shares in lieu of Shire ADSs as set forth in
Section 2.5(f).  Upon surrender of any such certificate for cancellation to the
Exchange Agent, together with such letter of transmittal, duly executed, the
holder of such certificate shall be entitled to receive in exchange therefor the
Merger Consideration.  Shire shall cause the Depositary to issue Shire ADRs
through and upon the instructions of the Exchange Agent, for the benefit of the
holders of shares of Common Stock who have not elected to receive Ordinary
Shares pursuant to Section 2.5(f).  Neither the Exchange Agent nor any party
hereto shall be liable to any Holder for any amount paid to a public official
pursuant to any applicable abandoned property, escheat or similar law.  Shire
and the Exchange Agent shall be entitled to deduct and withhold from the
consideration otherwise payable pursuant to this Agreement to any Holder such
amounts as the Surviving Corporation or the Exchange Agent is required to deduct
and withhold under the Code or any provision of national, state or local law,
with respect to the making of such payment.  To the extent such amounts are so
withheld, such withheld amounts shall be treated for all purposes of this
Agreement as having been paid
<PAGE>

                                      -15-

to the Holder in respect of whom such deduction and withholding was made. Any
Merger Consideration payable to Holders pursuant to Section 2.5 which remains
undistributed to the Holders for a period of six months after the Closing Date
shall be delivered to the Surviving Corporation upon its request, and any
Holders who have not surrendered to the Exchange Agent certificates for Common
Stock or complied with the instructions in the letter of transmittal, as the
case may be, shall thereafter look only to the Surviving Corporation for payment
of such Merger Consideration. The Surviving Corporation shall instruct the
Exchange Agent to invest all cash held by it in Cash Equivalents. Interest
earned on such Cash Equivalents shall be paid to the Surviving Corporation.

          (c)  Until so surrendered, each certificate representing Common Stock
shall represent, after the Effective Time, solely the right to receive the
Merger Consideration specified in Section 2.5.  The Merger Consideration issued
upon the surrender of Common Stock in accordance with the terms hereof shall be
deemed to have been issued in full satisfaction of all rights pertaining to such
Common Stock (and associated Rights).

          2.7.  Consideration for Ordinary Shares.  The consideration for the
                ---------------------------------
allotment by Shire of Ordinary Shares constituting the Merger Consideration
shall be the cancellation of all shares of Common Stock pursuant to Section
2.6(a).

          2.8.  Tax-Free Reorganization.  For U.S. income tax purposes, the
                -----------------------
parties intend that the Merger be treated as a tax-free reorganization pursuant
to the provisions of Section 368(a)(1)(A) and Section 368(a)(2)(E) of the Code.
Each party hereto agrees not to take any position inconsistent with the
foregoing on any Tax Return, unless required by law.

                                  ARTICLE III


                         REPRESENTATIONS AND WARRANTIES

          3.1.  Representations and Warranties of Roberts.  Roberts represents
                -----------------------------------------
and warrants to Shire and Acquisition Sub that, except (A) as set forth in the
Roberts Disclosure Schedule delivered by Roberts to Shire at or prior to the
execution of this Agreement (the "Roberts Disclosure Schedule") (each section of
                                  ---------------------------
which qualifies the correspondingly numbered representation and warranty) and
(B) with respect to paragraphs (j), (m), (o), (p), (q), (r), (t), (w), (x) and
(y) of this Section
<PAGE>

                                      -16-

3.1, as does not have, or could not reasonably be expected to have, individually
or in the aggregate, a Roberts Material Adverse Effect, the following is true
and correct:

          (a)  Organization; Standing and Power.  Roberts is a corporation duly
               --------------------------------
     organized, validly existing and in good standing under the laws of the
     State of New Jersey.  Roberts has all requisite corporate power and
     authority to own, lease and operate its assets and to carry on its business
     as now being conducted.  Roberts is duly qualified as a foreign corporation
     to do business, and is in good standing, in each jurisdiction where the
     character of its assets owned or leased or the nature of its activities
     makes such qualification necessary (such jurisdictions being specified in
     Section 3.1(a) of the Roberts Disclosure Schedule) except where the failure
     to be so qualified would not have a Roberts Material Adverse Effect.
     Copies of the Certificate of Incorporation and By-Laws of Roberts as in
     effect on the date hereof have been previously delivered to Shire.

          (b)  Subsidiaries and Investments.  Section 3.1(b) of the Roberts
               ----------------------------
     Disclosure Schedule lists each Subsidiary of Roberts.  Each such Subsidiary
     is a corporation duly organized, validly existing and (in applicable
     jurisdictions) in good standing under the laws of its jurisdiction of
     incorporation.  Each such Subsidiary has all requisite corporate power and
     authority to own, lease and operate its assets and to carry on its business
     as now being conducted.  All such Subsidiaries are duly qualified as
     foreign corporations to do business, and (in applicable jurisdictions) are
     in good standing, in each jurisdiction where the character of their
     respective assets owned or leased or the nature of their respective
     activities makes such qualification necessary, except where the failure to
     be so qualified or in good standing would not have a Roberts Material
     Adverse Effect.  All the outstanding shares of capital stock of each such
     Subsidiary have been validly issued and are fully paid (and in applicable
     jurisdictions, nonassessable) and are owned by Roberts, by another
     Subsidiary of Roberts or by Roberts and another such Subsidiary, free and
     clear of all Liens, other than Liens which (individually or in the
     aggregate) would not have a Roberts Material Adverse Effect.  Except for
     the capital stock of its Subsidiaries, Roberts does not own any stock,
     partnership or other equity interest in, or any debt or equity securities
     of, any person or entity.
<PAGE>

                                      -17-

          (c)  Capitalization.  The authorized capital stock of Roberts
               --------------
     consists of 110,000,000 shares of capital stock, including 10,000,000
     shares of Class B Preferred Stock par value $.10 per share (of which
     5,500,000 shares have been designated as Series B 5% Convertible Preferred
     Stock, all of which have been converted into Common Stock), 500,000 shares
     of Series A Junior Participating Preferred Stock par value $.10 per share
     and 100,000,000 shares of Common Stock.  At the close of business on July
     21, 1999 (i) 31,889,077 shares of Common Stock were issued and outstanding,
     (ii) 387,594 shares of Common Stock were held by Roberts in its treasury,
     (iii) 3,353,188 shares of Common Stock were reserved for issuance on
     exercise of outstanding options under the Roberts Option Plans, (iv) 150
     shares of Common Stock were reserved for issuance upon the exercise of the
     warrant issued to A.B. Laffer, V.A. Canto & Associates and (v) 500,000
     shares of Series A Junior Participating Preferred Stock were reserved for
     issuance under the Rights Agreement and no other shares of capital stock
     were issued, reserved for issuance or outstanding.  All outstanding shares
     of capital stock of Roberts are, and all shares which are reserved for
     issuance will be, when issued in accordance with the Roberts Option Plans,
     duly authorized, validly issued, fully paid and nonassessable and not
     subject to preemptive rights.  Except as set forth above, as of the date of
     this Agreement, there are not any securities convertible into or
     exchangeable or exercisable for capital stock ("Equity Equivalent") of any
                                                     -----------------
     of Roberts or any of its Subsidiaries (including, without limitation, any
     option, warrant, right to subscribe, call or commitment of any kind or
     character whatsoever requiring the issuance, sale or transfer by Roberts or
     any of its Subsidiaries of any shares of their capital stock or any
     securities convertible into or exchangeable or exercisable for such capital
     stock).  As of the date of this Agreement, there are not any outstanding
     contractual obligations of Roberts or any of its Subsidiaries to
     repurchase, redeem or otherwise acquire any shares of capital stock of
     Roberts or any of its Subsidiaries.  Roberts has delivered to Shire a
     complete and correct copy of the Rights Agreement as amended and
     supplemented to the date of this Agreement.  There are no outstanding stock
     appreciation, phantom stock, profit participation or similar rights
     (collectively, "SARs") with respect to Roberts.  Roberts has delivered to
                     ----
     Shire a complete list of all outstanding Indebtedness of Roberts and its
     Subsidiaries.
<PAGE>

                                      -18-

          (d)  Authority.  Roberts has the requisite corporate power and
               ---------
     authority to execute and deliver this Agreement and, subject to Roberts
     Shareholder Approval (as defined below) and the receipt of the consents and
     waivers set forth in Section 3.1(d) of the Roberts Disclosure Schedule, to
     consummate the transactions contemplated by this Agreement to be
     consummated by Roberts.  The execution and delivery of this Agreement by
     Roberts and the consummation of the transactions contemplated hereby have
     been duly authorized by all necessary corporate action on the part of
     Roberts, subject to the approval of this Agreement and the transactions
     contemplated hereby by the affirmative vote of holders of at least two-
     thirds of the shares of Common Stock voted at a meeting (the "Roberts
                                                                   -------
     Shareholder Approval").  This Agreement has been duly executed and
     --------------------
     delivered by Roberts and constitutes a valid and binding obligation of
     Roberts, enforceable against Roberts in accordance with its terms, subject
     to applicable bankruptcy, insolvency moratorium or other similar laws
     relating to creditors' rights and general principles of equity.

          (e)  Noncontravention.  Neither the execution and delivery of this
               ----------------
     Agreement by Roberts nor the consummation of the transactions contemplated
     hereby nor compliance by Roberts with any of the provisions hereof will (i)
     violate, conflict with or result in a breach of any provision of, or
     constitute a default (or an event which, with notice or lapse of time or
     both, could constitute a default) under, or result in the termination,
     modification or suspension of, or accelerate the performance required by,
     or result in a right of termination or acceleration under, or result in the
     creation of any Lien upon, right to acquire or obligation to dispose of any
     of the properties, assets or rights of Roberts or any of its Subsidiaries
     under, any of the terms, conditions or provisions of (x) the Certificate of
     Incorporation or By-Laws of Roberts or any of its Subsidiaries or (y) any
     note, bond, mortgage, credit agreement, indenture, deed of trust, license,
     Permit, authorization, lease, agreement or instrument or obligation to
     which Roberts or any of its Subsidiaries is party or by which they are
     bound or to which they or any of their assets may be subject, or (ii)
     violate any judgment, ruling, order, writ, injunction, decree, statute,
     rule or regulation applicable to Roberts or any of its Subsidiaries, their
     operations or any of their assets, except for such violations, conflicts or
     breaches referred to in clauses (i)(y) and (ii) which would not,
     individually or in the aggregate, have a Roberts Material Adverse Effect.
<PAGE>

                                      -19-

          (f)  Government Approval; Consents.  No consents and approvals are
               -----------------------------
     required to be obtained by Roberts from non-governmental third parties

     ("Roberts Third Party Approvals") in order to lawfully and contractually
     -------------------------------
     permit it to perform its obligations under this Agreement and consummate
     the transactions contemplated hereby.  No notice to, filing with, or
     authorization, consent or approval of, any federal, state, local or non-
     U.S. public body or authority is necessary for the execution, delivery or
     performance of this Agreement by Roberts or the consummation of the
     transactions contemplated hereby ("Roberts Governmental Approvals").
                                        ------------------------------

          (g)  SEC Documents. (i) Roberts has filed all required reports,
               -------------
     schedules, forms, statements and other documents with the SEC since January
     1, 1998 (the "SEC Documents").  As of their respective dates, the SEC
                   -------------
     Documents complied in all material respects with the requirements of the
     Securities Act or the Exchange Act, as the case may be, and the rules and
     regulations of the SEC promulgated thereunder applicable to such SEC
     Documents, and none of the SEC Documents contained any untrue statement of
     a material fact or omitted to state a material fact required to be stated
     therein or necessary in order to make the statements therein, in the light
     of the circumstances under which they were made, not misleading.  The
     financial statements of Roberts included in the SEC Documents comply as to
     form in all material respects with applicable accounting requirements and
     the published rules and regulations of the SEC with respect thereto, have
     been prepared in accordance with accounting principles generally accepted
     in the United States ("US GAAP") (except, in the case of unaudited
                            -------
     statements, as permitted by Form 10-Q of the SEC) applied on a consistent
     basis during the periods involved (except as may be indicated in the notes
     thereto) and fairly present the consolidated financial position of Roberts
     and its consolidated Subsidiaries as of the dates thereof and the
     consolidated results of their operations and cash flows for the periods
     then ended (subject, in the case of unaudited statements, to normal year-
     end audit adjustments).

             (ii) Roberts is eligible to use Form S-3 for the filing of a
     registration statement with the SEC under the Securities Act.

          (h)  Information Supplied. None of the information supplied or to be
               --------------------
     supplied by Roberts for inclusion or
<PAGE>

                                      -20-

     incorporation by reference in (i) the registration statement on Form F-4 to
     be filed with the SEC by Shire in connection with the issuance of Ordinary
     Shares and Shire ADSs in the Merger (the "Form F-4") will, at the time the
                                               --------
     Form F-4 is filed with the SEC, at any time it is amended or supplemented
     or at the time it becomes effective under the Securities Act, contain any
     untrue statement of a material fact or omit to state any material fact
     required to be stated therein or necessary to make the statements therein
     not misleading, (ii) the UK Disclosure Documents will, on the date the UK
     Disclosure Documents are first mailed to the shareholders of Shire or at
     the time of the Shire shareholders meeting, contain any untrue statement of
     a material fact or omit to state any material fact required to be stated
     therein or necessary in order to make the statements therein, in the light
     of the circumstances under which they are made, not misleading or (iii) the
     Proxy Statement will, at the date it is first mailed to Roberts
     shareholders or at the time of the Roberts Shareholders Meeting, contain
     any untrue statement of a material fact or omit to state any material fact
     required to be stated therein or necessary in order to make the statements
     therein, in the light of the circumstances under which they are made, not
     misleading. The Proxy Statement will comply as to form in all material
     respects with the requirements of the Exchange Act and the rules and
     regulations thereunder, except that no representation is made by Roberts
     with respect to statements made or incorporated by reference therein based
     on information supplied by Shire.

          (i)  Absence of Certain Changes or Events.  Except as disclosed in
               ------------------------------------
     the SEC Documents filed and publicly available prior to the date of this
     Agreement (the "Filed SEC Documents"), since December 31, 1998 there has
                     -------------------
     not been (i) any material adverse change in the business, financial
     condition or results of operations of Roberts and its Subsidiaries, taken
     as a whole, (ii) any destruction or loss of (whether or not covered by
     insurance) any property, asset or right that has had or is likely to have a
     Roberts Material Adverse Effect, (iii) any authorization or issuance by
     Roberts of any of its capital stock or the issuance of any debt security or
     other evidence of Indebtedness of Roberts or any of its Subsidiaries, (iv)
     any redemption or other acquisition by Roberts of any of its capital stock
     or by Roberts or any of its Subsidiaries of any of their debt securities or
     other evidences of Indebtedness, or any payment made with respect to any of
     the foregoing (other than any regular, periodic payment of
<PAGE>

                                      -21-

     interest made with respect to a debt security or other evidence of
     Indebtedness), (v) any declaration, setting aside or payment of any
     dividend or other distribution or payment (whether in cash, capital stock
     or otherwise) in respect of any capital stock of Roberts, (vi) any disposal
     or lapse of any Roberts Intellectual Property, (vii) any Lien (other than a
     Permitted Lien) incurred on any material property, assets or rights of
     Roberts or any of its Subsidiaries, (viii) any incurrence by Roberts or any
     of its Subsidiaries of any liability which has had or is likely to have a
     Roberts Material Adverse Effect, (ix) any incurrence of Indebtedness or any
     guarantee by Roberts or any of its Subsidiaries of any liability of any
     other person or entity outside of the ordinary course of business, (x) to
     the knowledge of Roberts, any development with respect to regulatory
     approval of any products of Roberts or any of its Subsidiaries which has
     had or is likely to have a Roberts Material Adverse Effect, (xi) to the
     knowledge of Roberts, any development with respect to relationships with
     any contract manufacturer or contract research organization with which
     Roberts or any of its Subsidiaries has a business relationship which has
     had or is likely to have a Roberts Material Adverse Effect or (xii) any
     change in Roberts' Tax accounting methods, any new election made with
     respect to Taxes, any modification or revocation of any existing election
     made with respect to Taxes, or any settlement or other disposition of any
     Tax matter.

          (j)  Compliance with Law.  Neither Roberts nor any of its
               -------------------
     Subsidiaries is in violation or noncompliance in any material respect with
     any statute, law, ordinance, regulation, rule, order or other legal
     requirement of any government, authority or any other governmental
     department or agency applicable to its business or operations, or any
     judgment, decree or order of any court to which it is a party.

          (k)  Affiliate Arrangements. Neither Roberts nor any of its
               ----------------------
     Subsidiaries is a party to any contract, agreement, arrangement,
     understanding or other commitment with any director, officer or
     securityholder of Roberts or any of its Subsidiaries or, to the knowledge
     of Roberts, any person or entity controlled by any such person.

          (l)  Transaction Fees.  Roberts has not retained any broker, finder,
               ----------------
     financial adviser, investment banker or other person or entity which is
     entitled to any brokerage,
<PAGE>

                                      -22-

     finder's or similar fee or commission in connection with this Agreement or
     the transactions contemplated hereby.

          (m)  Litigation.  There is no claim, action, suit or proceeding
               ----------
     pending or, to the knowledge of Roberts, threatened against Roberts or any
     of its Subsidiaries or any of their respective properties, assets or rights
     before any court or governmental or regulatory authority or body.

          (n)  Taxes and Tax Returns.  (i) Roberts has duly and timely filed
               ---------------------
     all federal, state, local and non-U.S. Tax Returns required to be filed by
     it and its Subsidiaries, and each such Tax Return is complete and accurate
     in all material respects, (ii) Roberts has timely paid all Taxes due and
     payable by it and its Subsidiaries and has made adequate provision (through
     a current accrual on its most recent financial statements) for any Taxes
     that are not yet due and payable and (iii) Roberts has withheld and paid in
     a timely manner all Taxes required to have been withheld and paid in
     connection with amounts paid or owing to any employee, independent
     contractor, creditor, stockholder or other third party, including amounts
     of or the value of awards and prizes paid to Roberts' employees.  Any
     deficiencies or assessments asserted in writing by any taxing authority
     have been paid or fully settled and no issue raised by any such taxing
     authority reasonably could be expected to result in a proposed deficiency
     for any prior, parallel or subsequent period (including periods subsequent
     to the Effective Time).  There are no claims or assessments pending (or, to
     the best knowledge of Roberts, threatened) against Roberts or any of its
     Subsidiaries for any alleged federal, state, local or non-U.S. Tax
     deficiency and no issue has been raised in writing by any federal, state,
     local or non-U.S. taxing authority or representative thereof.  No consent
     has been filed relating to Roberts pursuant to Section 341 of the Code.  No
     claim has ever been made by an authority in a jurisdiction where Roberts
     does not file Tax Returns that it is or may be subject to taxation by that
     jurisdiction.  Section 3.1(n) of the Roberts Disclosure Schedule lists all
     federal, state, local and non-U.S. jurisdictions in which Roberts files Tax
     Returns, and indicates those Tax Returns that have been audited and those
     that currently are the subject of audit.  Roberts has not consented to an
     extension of the statute of limitations with respect to any Tax period.
     Roberts is not a party to any Tax allocation or sharing agreement.  Roberts
     (i) has never been a member of an
<PAGE>

                                      -23-

     "affiliated group" (within the meaning of Section 1504 of the Code) and has
     never been a member of any combined, consolidated, affiliated or unitary
     group for any state, local or non-U.S. Tax purposes and (ii) has no
     liability for the Taxes of any person under Treas. Reg. (S) 1.1502-6 (or
     any similar provision of state, local or non-U.S. law), as a transferee or
     successor, by contract, or otherwise. Roberts has never had any
     "undistributed personal holding company income" (as defined in Section 545
     of the Code). Roberts is not required to make any adjustment pursuant to
     Section 481 of the Code (or any comparable provision of state, local or
     non-U.S. law) by reason of a change in accounting method or otherwise.
     Roberts has never requested a ruling from, or entered into a closing
     agreement with, the Internal Revenue Service or any other taxing authority.
     None of Roberts' assets is "tax-exempt use property" (as defined in Section
     168(h)(1) of the Code) or may be treated as owned by any other person
     pursuant to Section 168(f)(8) of the Internal Revenue Code of 1954 (as in
     effect immediately prior to the enactment of the Tax Reform Act of 1986).
     Roberts is not a party to any agreement or arrangement that provides for
     the payment of any amount that could constitute a "parachute payment"
     within the meaning of Section 280G of the Code. Roberts is not, and has
     never been, a "United States real property holding corporation" within the
     meaning of Section 897 of the Code. Roberts has not made any elections
     under Section 108, 168, 338, 441, 472, 1017, 1033 or 4977 of the Code (or
     any predecessor provisions thereof). Roberts has previously delivered to
     Shire true and complete copies of (i) all federal, state, local and non-
     U.S. income or franchise Tax Returns for each of the last three taxable
     years ending prior to the date of this Agreement (except for those Tax
     Returns that have not yet been filed) and (ii) any audit reports issued
     within the last three years by the Internal Revenue Service or any other
     taxing authority.

          (o)  Real Property.  Section 3.1(o) of the Roberts Disclosure
               -------------
     Schedule sets forth a complete and accurate list of all material real
     property owned or leased by Roberts or any of its Subsidiaries, including
     (i) with respect to owned real property, the date of its acquisition, any
     Liens on or with respect to such real property (other than Permitted
     Liens), the name of the holder of any such Lien and the amount and nature
     of any obligation secured by any such Lien and (ii) with respect to leased
     real property, the name of the lessor of such real property, a
<PAGE>

                                      -24-

     list of all instruments and documents governing the terms of such leasehold
     interest, any Lien on or with respect to such leasehold interest (other
     than Permitted Liens), the name of the holder of any such Lien and the
     amount and nature of any obligation secured by any such Lien. Roberts is
     not a lessor with respect to any material real property owned by it or any
     of its Subsidiaries and has not granted any sublease of any leasehold
     interest in any material real property leased by it or any of its
     Subsidiaries. With respect to such material real property, (i) there are no
     eminent domain proceedings pending or threatened against it, (ii) such
     properties and the improvements thereon (including the roof and structural
     portions of each building) are in good operating order and condition,
     subject to ordinary wear and tear, and (iii) the use thereof does not
     violate any zoning or similar land use laws or other government regulations
     other than such violations which, individually or in the aggregate, would
     not adversely affect the ability of the Surviving Corporation to use,
     operate or occupy any of such properties following the Effective Time. The
     real property owned or leased by Roberts and its Subsidiaries is sufficient
     for the conduct of its business.

          (p)  Licenses, Permits and Authorizations.  Section 3.1(p) of the
               ------------------------------------
     Roberts Disclosure Schedule sets forth a complete and accurate list of all
     material Permits held by or on behalf of Roberts and its Subsidiaries,
     including (i) the agency or body issuing such Permit, (ii) the person or
     entity to whom such Permit was issued and (iii) the date such Permit
     expires or is required to be renewed.  Each such Permit is, to the
     knowledge of Roberts, in full force and effect and Roberts, or the person
     or entity who holds such Permit on Roberts' behalf, is in compliance in all
     material respects with all of its obligations with respect thereto, and, to
     the knowledge of Roberts, no event has occurred or condition exists which
     permits or, upon the giving of notice or lapse of time or both, would
     permit revocation, nonrenewal, modification, suspension or termination of
     any such Permit.

          (q)  ERISA and Employee Matters.  Section 3.1(q) of the Roberts
               --------------------------
     Disclosure Schedule sets forth a complete and accurate list of all
     employment and consultancy agreements, all employee benefit plans (within
     the meaning of Section 3(3) of ERISA) or retirement benefits scheme (within
     the meaning of Section 611 of the Income and Corporation Taxes Act 1988)
     and all other written plans,
<PAGE>

                                      -25-

     arrangements or policies relating to stock options, stock purchases,
     compensation, deferred compensation, supplemental retirement arrangements,
     other incentive programs, severance, fringe benefits or other employee
     benefits (collectively "Employment Obligations") covering all present and
                             ----------------------
     former officers, directors, employees, consultants and agents of Roberts
     and its Subsidiaries and any of their spouses or dependents. Roberts has
     made available to Shire true, complete and correct copies of (i) each such
     Employment Obligation, (ii) the most recent annual report on Form 5500 as
     filed with the Internal Revenue Service with respect to each applicable
     Employment Obligation, (iii) the most recent summary plan description (or
     similar document) with respect to each applicable Employment Obligation,
     (iv) each trust agreement and insurance or annuity contract relating to any
     Employment Obligation and (v) the most recent actuarial valuation report
     for each applicable Employment Obligation. (i) Roberts and its Subsidiaries
     are in compliance in all material respects with all applicable provisions
     of the Employee Retirement Income Security Act of 1974, as amended
     ("ERISA"), and the Code with respect to each Employment Obligation, (ii)
       -----
     except for PBGC premiums, all of which that are due have been paid, neither
     Roberts nor any of its Subsidiaries has material liability under Title IV
     of ERISA, (iii) neither Roberts nor any of its Subsidiaries has engaged in
     a prohibited transaction or breach of fiduciary duty that would subject it
     to a material tax imposed under Section 4975 of the Code or material
     liability pursuant to Section 409 or 502 of ERISA, (iv) neither Roberts nor
     any of its Subsidiaries has been a party to or contributed to any
     "multiemployer plan" as defined in Section 4001(a) of ERISA, (v) no pension
     plan covering any present or former officers, directors or employees of
     Roberts or any of its Subsidiaries is or has been subject to Title IV of
     ERISA, (vi) except for liability for contributions and benefits pursuant to
     the Employment Obligations, neither Roberts nor any of its Subsidiaries has
     incurred any material liability under or pursuant to Title I or IV of ERISA
     or the penalty, excise tax or joint and several liability provisions of the
     Code relating to employee benefit plans and (vii) except claims for
     benefits payable in the normal operation of such Employment Obligations,
     there are no investigations by any governmental agency, termination
     proceedings or other claims, suits or proceedings against or involving any
     such Employment Obligation or asserting any rights to or claims for
     benefits under any such Employment Obligation. In respect of any Employment
     Obligations
<PAGE>

                                      -26-

     benefiting Roberts UK employees, (i) the only benefits provided are defined
     contribution benefits and no promise, assurance or undertaking has been
     given to any of the employees (whether legally binding or not) as to the
     provision of retirement, death or disability benefits at a particular
     level, (ii) there are not in respect of any retirement benefits scheme or
     the benefits under it any actions, suits or claims pending or threatened
     (other than routine claims or benefits) against the trustees or
     administrators of that scheme or against Shire. Each Employment Obligation
     of Roberts and its Subsidiaries (if any) that is intended to be a tax-
     qualified plan has been the subject of a determination letter from the
     Internal Revenue Service to the effect that such Employment Obligation and
     each related trust is qualified and exempt from Federal income taxes under
     Sections 401(a) and 501(a), as applicable, respectively, of the Code, no
     such determination letter has been revoked, and revocation has not been
     threatened and no event has occurred and no circumstances exist that would
     reasonably be expected to adversely affect the tax qualification of such
     Employment Obligation. Each of the Employment Obligations with respect to
     employees or former employees employed by Roberts or any of its
     Subsidiaries outside of the United States are in compliance in all material
     respects with all applicable law (including, where applicable, Article 141
     of the Treaty of Rome) and, to the extent not mandated by the laws of the
     applicable jurisdiction, copies of the applicable written plan document
     have been made available to Shire.

          (r)  Labor Relations.  (i) There is no unfair labor practice
               ---------------
     complaint pending against Roberts or any of its Subsidiaries or, to the
     knowledge of Roberts, threatened against them, before the National Labor
     Relations Board or any other U.S. or non-U.S. governmental or regulatory
     authority, and, to the knowledge of Roberts, no grievance or arbitration
     proceeding arising out of or under any of their Employment Obligations is
     so pending against Roberts or any of its Subsidiaries or threatened against
     them; (ii) to the knowledge of Roberts, there is no basis for an unfair
     labor practice finding against Roberts or any of its Subsidiaries; (iii) no
     strike, labor dispute, slowdown or stoppage is pending or, to the knowledge
     of Roberts, threatened against Roberts or any of its Subsidiaries; and (iv)
     no union has ever represented any employee of Roberts or any of its
     Subsidiaries.
<PAGE>

                                      -27-

          (s)  Intellectual Property Rights.  (i)  Section 3.1(s) of the
               ----------------------------
     Roberts Disclosure Schedule sets forth a complete and accurate list
     (including registration numbers and dates of filing, renewal and
     termination, where applicable, for each jurisdiction where filed) of all
     patents, patent applications, trademarks, trademark registrations and
     applications, copyrights, copyright applications, service marks, service
     mark registrations and applications and trade names (whether or not
     registered or registrable) ("Intellectual Property") owned by Roberts or
                                  ---------------------
     any of its Subsidiaries which is material to Roberts and its Subsidiaries,
     taken as a whole ("Roberts Intellectual Property"), including any Liens
                        -----------------------------
     thereon, the name of the holder of any such Lien and the amount and nature
     of any obligation secured by any such Lien.  All Roberts Intellectual
     Property is owned by Roberts or its Subsidiaries free and clear of all
     Liens, no Roberts Intellectual Property has been canceled, abandoned or
     otherwise terminated and all patent applications, trademark applications
     and copyright applications included in Roberts Intellectual Property have
     been duly filed and are recorded on the public record in the name of
     Roberts or one of its Subsidiaries and all renewal fees have been duly paid
     other than where such action would not have a Roberts Material Adverse
     Effect.  Neither Roberts nor any of its Subsidiaries has granted any
     license or other rights with respect to any Roberts Intellectual Property
     to any other person or entity.

             (ii) Roberts has no knowledge that any of its or its Subsidiaries'
     granted patents are invalid; to the knowledge of Roberts, no Roberts
     Intellectual Property is being infringed by any third party in any material
     respect; and, to the knowledge of Roberts, its current operations do not
     infringe a granted patent of a third party in any material respect.

             (iii)  Neither Roberts nor any of its Subsidiaries has any license
     or other rights with respect to any Intellectual Property owned by any
     other person or entity.

             (iv) All technology, processes, techniques and methods of
     manufacture used in or necessary to the manufacturing or research
     operations of Roberts and its Subsidiaries, except to the extent the same
     are in the public domain, are subject to valid and effective
     confidentiality agreements between Roberts and its employees, have been
     memorialized to the extent required by good manufacturing practice and, to
     the knowledge of Roberts, are the subject
<PAGE>

                                      -28-

     of no claim, whether or not asserted, that their use or employment by
     Roberts or any of its Subsidiaries violates the rights of any person.

          (t)  Insurance.  Section 3.1(t) of the Roberts Disclosure Schedule
               ---------
     sets forth (i) a complete and accurate list of all policies of insurance of
     Roberts and its Subsidiaries currently in force, including surety bonds or
     other credit support therefor (the "Roberts Insurance Policies"), the
                                         --------------------------
     current annual premiums for each Roberts Insurance Policy, the types of
     risk covered and limits of coverage and (ii) a description of claims
     experience of Roberts (x) in the twelve months immediately preceding the
     date hereof with respect to all matters and (y) since its incorporation
     with respect to product liability matters, matters arising by reason of
     clinical trials, environmental matters and workmen's compensation.  All
     Roberts Insurance Policies are in full force and effect and all premiums
     due thereon have been paid.  Roberts has complied in all material respects
     with the terms and provisions of the Roberts Insurance Policies.  Roberts
     has never applied for and been refused or denied any policy of insurance
     with respect to product liability matters, matters arising by reason of
     clinical trials, environmental matters and workmen's compensation.
     Roberts' insurance coverage is adequate in kind and amount based on current
     industry practice.

          (u)  Books and Records.  (i)  The books of account and other
               -----------------
     financial records of Roberts and its Subsidiaries that have been made
     available to Shire prior to the date hereof or are made available
     thereafter are or will be true, complete and correct in all material
     respects and do not and will not contain any omissions which, in light of
     the circumstances in which they are made, are materially misleading.

             (ii) The minute books and other records of Roberts and its
     Subsidiaries that have been made available to Shire prior to the date
     hereof or are made available thereafter contain records of all meetings of
     Roberts and its Subsidiaries prior to the date hereof and prior to the
     Effective Time, respectively, are or will be accurate in all material
     respects and reflect accurately in all material respects all other
     corporate action of the shareholders and directors and any committees of
     the Board of Directors of Roberts and its Subsidiaries.
<PAGE>

                                      -29-

          (v)  Undisclosed Liabilities.  Except as set forth in the Filed SEC
               -----------------------
     Documents and except for liabilities and obligations incurred in the
     ordinary course of business consistent with past practice and U.S. GAAP,
     neither Roberts nor any of its Subsidiaries has any liabilities or
     obligations of any nature (whether accrued, absolute, contingent or
     otherwise) required by US GAAP to be set forth on a consolidated balance
     sheet of Roberts and its consolidated Subsidiaries or in the notes thereto
     and which, individually or in the aggregate, could reasonably be expected
     to have a Roberts Material Adverse Effect.

          (w)  FDA, DEA Matters.  Section 3.1(w) of the Roberts Disclosure
               ----------------
     Schedule sets forth a complete and accurate list of (i) each
     investigational new drug filing made by Roberts or any of its Subsidiaries
     with the U.S. Food and Drug Administration (the "FDA") or any non-U.S.
                                                      ---
     equivalent (including, without limitation, the U.K. Medicines Control
     Agency (the "MCA") and Health Protection Branch of the Ministry of Health
                  ---
     of Canada), (ii) each clinical trial protocol submitted by Roberts or any
     of its Subsidiaries to the FDA or any non-U.S. equivalents, (iii) each new
     drug application and abbreviated or supplemental new drug application filed
     by Roberts or any of its Subsidiaries pursuant to the Federal Food, Drug
     and Cosmetic Act, as amended, or any non-U.S. equivalents, (iv) each
     product license application filed by Roberts or any of its Subsidiaries
     pursuant to the Public Health Service Act, as amended, or any non-U.S.
     equivalents and (v) each establishment license application filed with
     respect to any product of Roberts or any of its Subsidiaries under the
     Public Health Service Act, as amended, or any non-U.S. equivalents.  (i)
     There are no lawsuits, arbitrations, legal or administrative or regulatory
     proceedings, charges, complaints or investigations by the FDA, the U.S.
     Drug Enforcement Agency (the "DEA"), the U.S. Department of Justice (the
                                   ---
     "DOJ") or any state or non-U.S. regulatory agency pending or, to the best
     ----
     knowledge of Roberts, threatened against or relating to Roberts, any of its
     Subsidiaries or any of their products, (ii) there have been no product
     recalls or similar actions by Roberts or any of its Subsidiaries, (iii)
     each clinical trial with respect to products of Roberts and its
     Subsidiaries has been conducted in accordance with its clinical trial
     protocol and applicable regulations and Roberts or one of its Subsidiaries
     has filed all required notices (and made available to Shire copies thereof)
     of adverse drug experiences, injuries or deaths relating to clinical trials
     of such prod-
<PAGE>

                                      -30-


     ucts, and Roberts or one of its Subsidiaries has filed all required notices
     of any such occurrence, (iv) to the best knowledge of Roberts, all clinical
     trials have been and are being conducted in substantial compliance with all
     applicable good clinical practice regulations, (v) neither Roberts nor any
     of its Subsidiaries nor, to the best knowledge of Roberts, any of their
     respective officers, employees or agents has made an untrue statement of
     material fact or fraudulent statement to the FDA, the MCA, the DEA or other
     regulatory agencies, failed to disclose a material fact required to be
     disclosed to any of them or committed an act, made a statement or failed to
     make a statement that could reasonably be expected to provide a basis for
     any of them to invoke the policy respecting "Fraud, Untrue Statements of
     Material Facts, Bribery and Illegal Gratuities" set forth in 56 Fed. Reg.
     46191 (September 10, 1991) or equivalent regulations, (vi) there are no
     unresolved reports, warning letters or other documents received from or
     issued by the FDA, the MCA, the DEA or other regulating agencies that
     indicate or suggest material lack of compliance with applicable regulatory
     requirements by Roberts, any of its Subsidiaries or persons providing
     services for the benefit of any of them, (vii) to the best knowledge of
     Roberts, no person has filed a claim for loss or potential loss under any
     indemnity covering participants in clinical trials of products of Roberts
     and its Subsidiaries, (viii) to Roberts' knowledge, no material
     modifications to the process by which products of Roberts or any of its
     Subsidiaries that have been or are being used in clinical trials are
     manufactured will be necessary in order to manufacture commercial
     quantities of such products, (ix) as to each drug of Roberts or any of its
     Subsidiaries for which a new drug application or abbreviated new drug
     application has been approved by the FDA or other regulating agencies, the
     applicant and all persons performing operations covered by the application
     are in substantial compliance with 21 U.S.C. Section 355 or 357, 21 C.F.R.
     Part 314 or 430 et seq. (or non-U.S. equivalents), respectively, and all
                     ------
     terms and conditions of the application, (x) Roberts and its Subsidiaries
     are in compliance with all applicable registration and listing requirements
     set forth in 21 U.S.C. Section 360 and 21 C.F.R. Part 207 and, to the
     extent required, Roberts or one of its Subsidiaries has obtained licenses
     from the DEA and is in compliance with all such licenses and all applicable
     regulations promulgated by the DEA, (xi) all manufacturing operations
     conducted by or, to the knowledge of Roberts, for the benefit of Roberts
     and its Subsidiaries
<PAGE>

                                      -31-

     have been and are being conducted in compliance with applicable good
     manufacturing practice regulations including those set forth in 21 C.F.R.
     Parts 210 and 211, (xii) neither Roberts nor any of its Subsidiaries has
     received any written notice that the FDA, the MCA, the DEA or other
     regulating agencies has commenced, or threatened to initiate, any action to
     withdraw its approval or request the recall of any product of Roberts or
     its Subsidiaries or withdraw advertising or sales promotion materials or
     commenced, or threatened to initiate, any action to enjoin production at
     any facility owned or used by Roberts or any of its Subsidiaries or any of
     their manufacturing locations, (xiii) as to each article of drug or
     consumer product currently manufactured and/or distributed by or on behalf
     of Roberts or its Subsidiaries, such article is not adulterated or
     misbranded within the meaning of the FDCA, 21 U.S.C. Sections 301 et seq.,
                                                                       ------
     and all advertising and sales promotional materials of Roberts or its
     Subsidiaries are otherwise in conformance with applicable regulations and
     (xiv) neither Roberts nor any of its Subsidiaries nor, to the knowledge of
     Roberts, any of their respective officers, employees, agents or affiliates
     has been convicted of any crime or engaged in any conduct for which
     debarment is mandated by 21 U.S.C. Section 335(a) or authorized by 21
     U.S.C. Section 335a(b). To the knowledge of Roberts, Roberts' contractors
     are in compliance with all applicable law and regulations and in respect of
     the FDA and DEA have secured all licenses, renewals and quotas necessary to
     their operation.

          Roberts has made available to Shire copies of all written
     communications to or from the FDA and the DEA relating specifically to
     Roberts, its Subsidiaries and their respective operations or business.

          (x)  Environmental Matters.  (i)  Each of Roberts and its
               ---------------------
     Subsidiaries possesses all Environmental Permits required under applicable
     Environmental Laws to conduct its business as currently conducted and to
     own and operate its assets, and is in compliance in all material respects
     with the terms and conditions of such Environmental Permits.

             (ii) The execution, delivery and performance of this Agreement and
     the consummation of the transactions contemplated hereby will not affect
     the validity or require the transfer of any Environmental Permits held by
     Roberts or its Subsidiaries, and will not require any notification,
<PAGE>

                                      -32-

     disclosure, registration, reporting, filing, investigation or remediation
     under any Environmental Law.

             (iii)  Each of Roberts and its Subsidiaries is in compliance in all
     material respects with all applicable Environmental Laws and has no
     material liability under any Environmental Law.

             (iv) There is no civil, criminal or administrative action, suit,
     demand, claim, hearing, notice of violation, proceeding, notice or demand
     letter, or request for information pending or, to the knowledge of Roberts
     threatened, under any Environmental Law (x) against Roberts or its
     Subsidiaries or (y) to the knowledge of Roberts against any person or
     entity in connection with which liability could reasonably be expected to
     be imputed or attributed by law or contract to Roberts or its Subsidiaries.

             (v) No property or facility presently or formerly owned, leased or
     operated by Roberts or its Subsidiaries, and no property or facility at
     which Hazardous Materials of Roberts or its Subsidiaries have been stored,
     treated or disposed of or at which any Hazardous Materials have been
     manufactured, handled, tested, formulated, prepared, encapsulated,
     packaged, bottled or stored for Roberts or its Subsidiaries ("Roberts
                                                                   -------
     Product Sites") is listed or proposed for listing on the National
     -------------
     Priorities List or the Comprehensive Environmental Response, Compensation
     and Liability Information System, both promulgated under the Comprehensive
     Environmental Response, Compensation and Liability Act of 1980, as amended
     ("CERCLA"), or on any comparable list established under any Environmental
       ------
     Law.

             (vi) There has been no disposal, spill, discharge, emission or
     release of any Hazardous Material by Roberts or its Subsidiaries on, at,
     under or from any property presently or formerly owned, leased or operated
     by Roberts or its Subsidiaries and there are no Hazardous Materials located
     in, at, on or under any such facility or property, or, to the knowledge of
     Roberts, at any Roberts Product Site or other location where Hazardous
     Materials of Roberts or any of its Subsidiaries have been stored, treated
     or disposed of (a "Roberts Third Party Site"), in each case that could
                        ------------------------
     reasonably be expected to result in the incurrence of any material
     liability, by Roberts or its Subsidiaries under any Environmental Law.
<PAGE>

                                      -33-

             (vii)  There are no underground storage tanks or other underground
     storage receptacles or related piping, or any impoundments containing
     Hazardous Materials located on any facility or property owned, leased or
     operated by Roberts or any of its Subsidiaries.

             (viii)  No Lien has been recorded against any properties, assets or
     facilities owned, leased or operated by Roberts or any of its Subsidiaries
     under any Environmental Law.

             (ix) Neither Roberts nor any of its Subsidiaries is obligated to
     perform any investigation or other action under any Environmental Law
     pursuant to any order, decree, judgment or agreement by which it is bound,
     or has assumed by contract or agreement any obligation or liability under
     any Environmental Law.

          Roberts has made available to Shire all material records and files,
     including, but not limited to, all assessments, reports, studies, audits,
     analyses, tests and data, in possession, custody or control of Roberts or
     its Subsidiaries concerning compliance by Roberts and its Subsidiaries
     with, or liability under, any Environmental Law, including, without
     limitation, those concerning the existence of Hazardous Materials at
     facilities or properties currently or formerly owned, operated or leased by
     Roberts or its Subsidiaries or at any Roberts Product Site or Roberts Third
     Party Site.

          (y)  Products.  Each of the products produced or sold by Roberts and
               --------
     its Subsidiaries:  (i) is, and at all times up to and including the date
     hereof has been, in compliance in all material respects with all applicable
     federal, state, local and non-U.S. laws and regulations; (ii) is, and at
     all relevant times has been, fit for the ordinary purposes for which it is
     intended to be used and conforms in all material respects to any promises
     or affirmations of fact made on the container, label or promotional
     materials for such product or in connection with its sale; and (iii)
     contains no design or manufacturing defect.  Neither Roberts nor any of its
     Subsidiaries has received notice of any product warranty claims.  Neither
     Roberts nor any of its Subsidiaries is aware of any facts which are
     reasonably likely to cause (i) the withdrawal or recall of any product sold
     or intended to be sold by Roberts or its Subsidiaries, (ii) a change in the
     marketing classification, labeling or promotional materials of any such
     products, or
<PAGE>

                                      -34-

     (iii) a termination or suspension of marketing of any such products. There
     are no material claims pending or, to the knowledge of Roberts, threatened
     against Roberts or its Subsidiaries with respect to the quality of or
     absence of defects in such products nor are there any facts known to
     Roberts relating to the quality of or absence of defects in such products
     which, if known by a potential claimant or governmental authority, could
     reasonably be expected to give rise to a claim or proceeding. To the
     knowledge of Roberts, no supplier of a raw material required for the
     manufacture of a material product of Roberts and its Subsidiaries for which
     there is not a permissible replacement obtainable under commercially
     reasonable terms has indicated that it will not continue to supply such raw
     material on terms consistent with those on the date hereof.

          (z)  Marketing Practices.  Roberts' operations and commercial conduct
               -------------------
     and those of its Subsidiaries have at all times conformed in all material
     respects to the Code of Marketing Practices of the Pharmaceutical Research
     Industry Association.

          (aa)  Affiliates.  Roberts has delivered to Shire a letter
                ----------
     identifying all persons who, as of the date hereof, may be deemed to be
     affiliates of Roberts for purposes of Rule 145 under the Securities Act
     ("Affiliates") and the written agreement of each such person in the form of
     ------------
     Exhibit 3 hereto.

          (bb)  Pooling.  Neither Roberts nor any of its Affiliates has taken
                -------
     or agreed to take any action or failed to take any action that would
     prevent the Merger from being treated for financial accounting purposes as
     a "pooling of interests" in accordance with US GAAP and the regulations and
     interpretations of the SEC.

          (cc)  Business Combination.  Neither the execution and delivery of
                --------------------
     this Agreement, the Option Agreement, the Shareholder Agreements nor the
     consummation of the transactions contemplated hereby or thereby, as the
     case may be, will (i) violate the Shareholder Protection Act or (ii) cause,
     directly or indirectly, a Triggering Event, as that term is defined in the
     Rights Agreement.

          3.2.  Representations and Warranties of Shire.  Shire represents and
                ---------------------------------------
warrants to Roberts that, except (A) as set forth in the Shire Disclosure
Schedule delivered by Shire to Roberts at or prior to the execution of this
Agreement (the
<PAGE>

                                      -35-

"Shire Disclosure Schedule") (each section of which qualifies the
 -------------------------
correspondingly numbered representation and warranty), and (B) with respect to
paragraphs (j), (m), (o), (p), (q), (r), (t), (w), (x) and (y) of this Section
3.2, as does not have, or could not reasonably be expected to have, individually
or in the aggregate, a Shire Material Adverse Effect, the following is true and
correct:

          (a)  Organization; Standing and Power.  Shire is a corporation duly
               --------------------------------
     organized and validly existing under the laws of the United Kingdom.  Shire
     has all requisite corporate power and authority to own, lease and operate
     its assets and to carry on its business as now being conducted.  Shire is
     duly qualified as a foreign corporation to do business in each jurisdiction
     where the character of its assets owned or leased or the nature of its
     activities makes such qualification necessary (such jurisdictions being
     specified in Section 3.2(a) of the Shire Disclosure Schedule) except where
     the failure to be so qualified would not have a Shire Material Adverse
     Effect.  Copies of the Memorandum and Articles of Association of Shire as
     in effect on the date hereof have been previously delivered to Roberts.
     Acquisition Sub is a corporation duly organized, validly existing and in
     good standing under the laws of the State of New Jersey.  Acquisition Sub
     has not conducted any activities other than in connection with its
     organization, the negotiation and execution of this Agreement and the
     consummation of the transactions contemplated hereby.

          (b)  Subsidiaries and Investments.  Section 3.2(b) of the Shire
               ----------------------------
     Disclosure Schedule lists each Subsidiary of Shire.  Each such Subsidiary
     is a corporation duly organized, validly existing and (in applicable
     jurisdictions) in good standing under the laws of its jurisdiction of
     incorporation.  Each such Subsidiary has all requisite corporate power and
     authority to own, lease and operate its assets and to carry on its business
     as now being conducted.  All such Subsidiaries are duly qualified as
     foreign corporations to do business, and (in applicable jurisdictions) are
     in good standing, in each jurisdiction where the character of their
     respective assets owned or leased or the nature of their respective
     activities makes such qualification necessary, except where the failure to
     be so qualified or in good standing would not have a Shire Material Adverse
     Effect.  All the outstanding shares of capital stock of each such
     Subsidiary have been validly issued and are fully paid (and in applicable
     jurisdic-
<PAGE>

                                      -36-

     tions, nonassessable) and are owned by Shire, by another Subsidiary
     of Shire or by Shire and another such Subsidiary, free and clear of all
     Liens, other than Liens which (individually or in the aggregate) would not
     have a Shire Material Adverse Effect.  Except for the capital stock of its
     Subsidiaries, Shire does not own any stock, partnership or other equity
     interest in, or any debt or equity securities of, any person or entity.

          (c)  Capitalization.  The authorized share capital of Shire as of the
               --------------
     date of this Agreement is (Pounds)10,000,000 divided into 200,000,000
     Ordinary Shares.  At the close of business on July 20, 1999 (i) 143,509,230
     Ordinary Shares were issued and (ii) the board of directors of Shire were
     generally and unconditionally authorized to allot relevant securities up to
     a nominal amount of (Pounds)2,361,070 and no other share capital was issued
     or reserved for issuance.  All such Ordinary Shares of Shire are, and all
     Ordinary Shares reserved for issuance will be, when issued, duly
     authorized, validly issued and fully paid and not subject to preemptive
     rights other than as required by law or the LSE rules.  The Ordinary Shares
     to be issued in the Merger will not be subject to preemption from existing
     shareholders of Shire.  Except as set forth above, as of the date of this
     Agreement, there are not any Equity Equivalents of any of Shire or any of
     its Subsidiaries (including, without limitation, any option, warrant, right
     to subscribe, call or commitment of any kind or character whatsoever
     requiring the issuance, sale or transfer by Shire or any of its
     Subsidiaries of any shares of their capital stock or any securities
     convertible into or exchangeable or exercisable for such capital stock).
     As of the date of this Agreement, there are not any outstanding contractual
     obligations of Shire or any of its Subsidiaries to repurchase, redeem or
     otherwise acquire any shares of capital stock of Shire or any of its
     Subsidiaries.  There are no outstanding SARs with respect to Shire.  Shire
     has delivered to Roberts a complete list of all outstanding indebtedness of
     Shire and its Subsidiaries.

          (d)  Authority.  Each of Shire and Acquisition Sub has the requisite
               ---------
     corporate power and authority to execute and deliver this Agreement and,
     subject to Shire Shareholder Approval (as defined below), to perform its
     respective obligations hereunder.  The execution and delivery of this
     Agreement by each of Shire and Acquisition Sub and the consummation of the
     transactions contemplated hereby have been duly authorized by the Board of
     Directors, or a
<PAGE>

                                      -37-

     duly authorized committee thereof, of each of Shire and Acquisition
     Sub. No other corporate proceedings on the part of Shire (other than the
     approval of this Agreement and the transactions contemplated hereby by the
     holders of not less than a majority of the Ordinary Shares present and
     voting or on a poll (the "Shire Shareholder Approval")) or Acquisition Sub
                               --------------------------
     are necessary to authorize the performance of this Agreement and the
     consummation of the transactions contemplated hereby. This Agreement has
     been duly executed and delivered by each of Shire and Acquisition Sub, and
     constitutes a valid and binding obligation of each of Shire and Acquisition
     Sub, enforceable in accordance with its terms, subject to applicable
     bankruptcy, insolvency, moratorium or other similar laws relating to
     creditors' rights and general principles of equity.

          (e)  Noncontravention.  Neither the execution and delivery of this
               ----------------
     Agreement by Shire or Acquisition Sub nor the consummation of the
     transactions contemplated hereby nor compliance by Shire or Acquisition Sub
     with any of the provisions hereof will (i) violate, conflict with or result
     in a breach of any provision of, or constitute a default (or an event
     which, with notice or lapse of time or both, could constitute a default)
     under, or result in the termination, modification or suspension of, or
     accelerate the performance required by, or result in a right of termination
     or acceleration under, or result in the creation of any Lien upon, right to
     acquire or obligation to dispose of any of the properties, assets or rights
     of Shire or any of its Subsidiaries under, any of the terms, conditions or
     provisions of (x) the Memorandum and Articles of Association of Shire or
     equivalent charter documents of any of its Subsidiaries or (y) any note,
     bond, mortgage, credit agreement, indenture, deed of trust, license,
     Permit, authorization, lease, agreement or instrument or obligation to
     which Shire or any of its Subsidiaries is party or by which they are bound
     or to which they or any of their assets may be subject, or (ii) violate any
     judgment, ruling, order, writ, injunction, decree, statute, rule or
     regulation applicable to Shire or any of its Subsidiaries, their operations
     or any of their assets, except for such violations, conflicts or breaches
     referred to in clauses (i)(y) and (ii) which would not, individually or in
     the aggregate, have a Shire Material Adverse Effect.

          (f)  Government Approval; Consents.  No consents and approvals are
               -----------------------------
     required to be obtained by Shire or Acquisi-
<PAGE>

                                      -38-

     tion Sub from non-governmental third parties ("Shire Third Party
                                                    -----------------
     Approvals") in order to lawfully and contractually permit it to perform its
     ---------
     obligations under this Agreement and consummate the transactions
     contemplated hereby. No notice to, filing with, or authorization, consent
     or approval of, any U.K. or non-U.K. public body or authority is necessary
     for the execution, delivery or performance of this Agreement by Shire or
     Acquisition Sub or the consummation of the transactions contemplated hereby
     ("Shire Governmental Approvals").
       ----------------------------

          (g)  Reports and Financial Statements.  (i) Shire has delivered to
               --------------------------------
     Roberts (A) its annual report for its fiscal year ended December 31, 1998,
     (B) all documents distributed to Shire's shareholders relating to meetings
     of the shareholders of Shire since January 1, 1998, and (C) all of its
     other reports and statements distributed to Shire shareholders together
     with copies of all prospectuses and listing particulars issued by Shire or
     any of its Subsidiaries since January 1, 1998 (the "Shire Documents").  As
                                                         ---------------
     of the date of its distribution to shareholders, each such report or
     statement distributed to shareholders did not contain any untrue statement
     of material fact or omit a material fact required to be stated therein or
     necessary to make the statements therein, in the light of the circumstances
     under which they were made, not misleading.  The audited consolidated
     financial statements of Shire included in the Shire Documents were prepared
     in accordance with accounting principles generally accepted in the United
     Kingdom ("UK GAAP") (except in the case of unaudited statements) applied on
               -------
     a consistent basis during the periods involved (except as may be indicated
     in the notes thereto), and present a true and fair view of the consolidated
     financial position of Shire and its consolidated Subsidiaries as of the
     dates of approval of such financial statements by the board of directors of
     Shire and the consolidated results of their operations and cash flows for
     the periods set forth therein.

          (h)  Information Supplied.  None of the information supplied or to be
               --------------------
     supplied by Shire for inclusion or incorporation by reference in (i) the
     Form F-4 will, at the time the Form F-4 is filed with the SEC, at any time
     it is amended or supplemented or at the time it becomes effective under the
     Securities Act, contain any untrue statement of a material fact or omit to
     state any material fact required to be stated therein or necessary to make
     the statements therein not misleading, (ii) the UK Disclosure
<PAGE>

                                      -39-

     Documents will, on the date the UK Disclosure Documents are first mailed to
     the shareholders of Shire, or at the time of the Shire shareholders meeting
     contain any untrue statement of a material fact or omit to state any
     material fact required to be stated therein or necessary in order to make
     the statements therein, in the light of the circumstances under which they
     are made, not misleading or (iii) the Proxy Statement will, at the date it
     is first mailed to Roberts shareholders or at the time of the Roberts
     Shareholders Meeting contain any untrue statement of a material fact or
     omit to state any material fact required to be stated therein or necessary
     in order to make the statements therein, in the light of the circumstances
     under which they are made, not misleading. The UK Disclosure Documents will
     contain all particulars relating to Shire and Roberts required to comply in
     all material respects with all United Kingdom statutory and other legal
     provisions (including, without limitation, the Companies Act, the FSA and
     the rules and regulations made thereunder and the rules and requirements of
     the LSE) and all such information contained in such documents will be
     substantially in accordance with the facts and will not omit anything
     material likely to affect the import of such information. The Form F-4 will
     comply as to form in all material respects with the requirements of the
     Securities Act and the rules and regulations thereunder, except that no
     representation is made by Shire with respect to statements made or
     incorporated by reference therein based on information supplied by Roberts.

          (i)  Absence of Certain Changes or Events.  Except as disclosed in
               ------------------------------------
     the Shire Documents filed and publicly available, or as disclosed in
     announcements made by Shire in compliance with the continuing obligations
     of the LSE prior to the date of this Agreement (the "Public UK Documents"),
                                                          -------------------
     since December 31, 1998 there has not been (i) any material adverse change
     in the business, assets, financial condition or results of operations of
     Shire and its Subsidiaries, taken as a whole, (ii) any destruction or loss
     of (whether or not covered by insurance) any property, asset or right that
     has had or is likely to have a Shire Material Adverse Effect, (iii) any
     authorization or issuance by Shire of any of its capital stock or the
     issuance of any debt security or other evidence of Indebtedness of Shire or
     any of its Subsidiaries, (iv) any redemption or other acquisition by Shire
     of any of its capital stock or by Shire or any of its Subsidiaries of any
     debt securities or other evidences of Indebtedness, or any pay-
<PAGE>

                                      -40-

     ment made with respect to any of the foregoing (other than any regular,
     periodic payment of interest made with respect to a debt security or other
     evidence of Indebtedness), (v) any declaration, setting aside or payment of
     any dividend or other distribution or payment (whether in cash, capital
     stock or otherwise) in respect of any capital stock of Shire, (vi) any
     disposal or lapse of any Shire Intellectual Property or Shire Intellectual
     Property License, (vii) any Lien (other than a Permitted Lien) incurred on
     any material property, assets or rights of Shire or any of its
     Subsidiaries, (viii) any incurrence by Shire or any of its Subsidiaries of
     any liability which has had or is likely to have a Shire Material Adverse
     Effect, (ix) any incurrence of Indebtedness or any guarantee by Shire or
     any of its Subsidiaries of any liability of any other person or entity
     outside of the ordinary course of business, (x) to the knowledge of Shire,
     any development with respect to regulatory approval of any products of
     Shire or any of its Subsidiaries which has had or is likely to have a Shire
     Material Adverse Effect, (xi) to the knowledge of Shire, any development
     with respect to relationships with any contract manufacturer or contract
     research organization with which Shire or any of its Subsidiaries has a
     business relationship which has had or is likely to have a Shire Material
     Adverse Effect or (xii) any change in Shire's Tax accounting methods, any
     new election made with respect to Taxes, any modification or revocation of
     any existing election made with respect to Taxes, or any settlement or
     other disposition of any Tax matter.

          (j)  Compliance with Law.  Neither Shire nor any of its Subsidiaries
               -------------------
     is in violation or non-compliance in any material respect with any statute,
     law, ordinance, regulation, rule, order or other legal requirement of any
     government, authority or any other governmental department or agency
     applicable to its business or operations, or any judgment, decree or order
     of any court to which it is a party.

          (k)  Affiliate Arrangements. Neither Shire nor any of its
               ----------------------
     Subsidiaries is a party to any contract, agreement, arrangement,
     understanding or other commitment with any director, officer or
     securityholder of Shire or any of its Subsidiaries or, to the knowledge of
     Shire, any person or entity controlled by any such person.

          (l)  Transaction Fees.  Shire has not retained any broker, finder,
               ----------------
     financial adviser, investment banker or
<PAGE>

                                      -41-

     other person or entity which is entitled to any brokerage, finder's or
     similar fee or commission in connection with this Agreement or the
     transactions contemplated hereby.

          (m)  Litigation.  There is no claim, action, suit or proceeding
               ----------
     pending or, to the knowledge of Shire, threatened against Shire or any of
     its Subsidiaries or any of their respective properties, assets or rights
     before any court or governmental or regulatory authority or body.

          (n)  Taxes and Tax Returns.  (i) Shire has duly and timely filed all
               ---------------------
     U.K. and non-U.K. Tax Returns required to be filed by it and its
     Subsidiaries, and each such Tax Return is complete and accurate in all
     material respects, (ii) Shire has timely paid all Taxes due and payable by
     it and its Subsidiaries and has made adequate provision (through a current
     accrual on its most recent financial statements) for any Taxes that are not
     yet due and payable and (iii) Shire has withheld and paid in a timely
     manner all Taxes required to have been withheld and paid in connection with
     amounts paid or owing to any employee, independent contractor, creditor,
     stockholder or other third party, including amounts of or the value of
     awards and prizes paid to Shire's employees.  Any deficiencies or
     assessments asserted in writing by any taxing authority have been paid or
     fully settled and no issue raised by any such taxing authority reasonably
     could be expected to result in a proposed deficiency for any prior,
     parallel or subsequent period (including periods subsequent to the
     Effective Time).  There are no claims or assessments pending (or, to the
     best knowledge of Shire, threatened) against Shire or any of its
     Subsidiaries for any alleged U.K. or non-U.K. Tax deficiency and no issue
     has been raised in writing by any U.K. or non-U.K. taxing authority or
     representative thereof.  No claim has ever been made by an authority in a
     jurisdiction where Shire does not file Tax Returns that it is or may be
     subject to taxation by that jurisdiction.  Section 3.2(n) of the Shire
     Disclosure Schedule lists all U.K. and non-U.K. jurisdictions in which
     Shire files Tax Returns, and indicates those Tax Returns that have been
     audited and those that currently are the subject of audit.  Shire has not
     consented to an extension of the statute of limitations with respect to any
     Tax period.  Shire is not a party to any Tax allocation or sharing
     agreement.  Shire (i) has never been a member of any combined,
     consolidated, affiliated or unitary group for any U.K. or non-U.K. Tax
     purposes and (ii) has no liability for the Taxes of any person as a
     transferee or
<PAGE>

                                      -42-

     successor, by contract, or otherwise. Shire has never requested a ruling
     from, or entered into a closing agreement with any taxing authority. Shire
     has previously delivered to Roberts true and complete copies of (i) all
     U.K. and non-U.K. income or franchise Tax Returns for each of the last
     three taxable years ending prior to the date of this Agreement (except for
     those Tax Returns that have not yet been filed) and (ii) any audit reports
     issued within the last three years by any taxing authority.

          (o)  Real Property.  Section 3.2(o) of the Shire Disclosure Schedule
               -------------
     sets forth a complete and accurate list of all material real property owned
     or leased by Shire or any of its Subsidiaries, including (i) with respect
     to owned real property, the date of its acquisition, any Liens on or with
     respect to such real property (other than Permitted Liens), the name of the
     holder of any such Lien and the amount and nature of any obligation secured
     by any such Lien and (ii) with respect to leased real property, the name of
     the lessor of such real property, a list of all instruments and documents
     governing the terms of such leasehold interest, any Lien on or with respect
     to such leasehold interest (other than Permitted Liens), the name of the
     holder of any such Lien and the amount and nature of any obligation secured
     by any such Lien.  Shire is not a lessor with respect to any material real
     property owned by it or any of its Subsidiaries and has not granted any
     sublease of any leasehold interest in any material real property leased by
     it or any of its Subsidiaries.  With respect to such material real
     property, (i) there are no eminent domain proceedings pending or threatened
     against it, (ii) such properties and the improvements thereon (including
     the roof and structural portions of each building) are in good operating
     order and condition, subject to ordinary wear and tear, and (iii) the use
     thereof does not violate any zoning or similar land use laws or other
     government regulations other than such violations which, individually or in
     the aggregate, would not adversely affect the ability of Shire and its
     Subsidiaries to use, operate or occupy any of such properties following the
     Effective Time.  The real property owned or leased by Shire and its
     Subsidiaries is sufficient for the conduct of their business.

          (p)  Licenses, Permits and Authorizations.  Section 3.2(p) of the
               ------------------------------------
     Shire Disclosure Schedule sets forth a complete and accurate list of all
     material Permits held by or on behalf of Shire and its Subsidiaries,
     including (i) the
<PAGE>

                                      -43-

     agency or body issuing such Permit, (ii) the person or entity to whom such
     Permit was issued and (iii) the date such Permit expires or is required to
     be renewed. Each such Permit is, to the knowledge of Shire, in full force
     and effect and Shire, or the person or entity who holds such Permit on
     Shire's behalf, is in compliance in all material respects with all of its
     obligations with respect thereto, and, to the knowledge of Shire, no event
     has occurred or condition exists which permits or, upon the giving of
     notice or lapse of time or both, would permit revocation, nonrenewal,
     modification, suspension or termination of any such Permit.

          (q)  ERISA and Employee Matters.  Section 3.2(q) of the Shire
               --------------------------
     Disclosure Schedule sets forth a complete and accurate list of all
     employment and consultancy agreements, all employee benefit plans (within
     the meaning of Section 3(3) of ERISA) or retirement benefits scheme (within
     the meaning of Section 611 of the Income and Corporation Taxes Act 1988)
     and all other written plans, arrangements or policies relating to stock
     options, stock purchases, compensation, deferred compensation, supplemental
     retirement arrangements, other incentive programs, severance, fringe
     benefits or other employee benefits (collectively "Shire Employment
                                                        ----------------
     Obligations") covering all present and former officers, directors,
     -----------
     employees, consultants and agents of Shire and its Subsidiaries and any of
     their spouses or dependents.  Shire has made available to Roberts true,
     complete and correct copies of (i) each Shire Employment Obligation, (ii)
     the most recent annual report on Form 5500 as filed with the Internal
     Revenue Service with respect to each applicable Shire Employment
     Obligation, (iii) the most recent summary plan description (or similar
     document) with respect to each applicable Shire Employment Obligation, (iv)
     each trust agreement and insurance or annuity contract relating to any
     Shire Employment Obligation and (v) the most recent actuarial valuation
     report for each applicable Shire Employment Obligation.  With respect to
     all Shire Employment Obligations benefiting Shire's U.S. employees, (i)
     Shire and its Subsidiaries are in compliance in all material respects with
     all applicable provisions of ERISA and the Code with respect to each Shire
     Employment Obligation, (ii) except for PBGC premiums, all of which that are
     due have been paid, neither Shire nor any of its Subsidiaries has any
     material liability under Title IV of ERISA, (iii) neither Shire nor any of
     its Subsidiaries has engaged in a prohibited transaction or breach of
     fiduciary duty that would
<PAGE>

                                      -44-

     subject it to a material tax imposed under Section 4975 of the Code or
     material liability pursuant to Section 409 or 502 of ERISA, (iv) neither
     Shire nor any of its Subsidiaries has been a party to or contributed to any
     "multiemployer plan" as defined in Section 4001(a) of ERISA, (v) no pension
     plan covering any present or former officers, directors or employees of
     Shire or any of its Subsidiaries is or has been subject to Title IV of
     ERISA, (vi) except for liability for contributions and benefits pursuant to
     such Shire Employment Obligations, neither Shire nor any of its
     Subsidiaries has incurred any material liability under or pursuant to Title
     I or IV of ERISA or the penalty, excise tax or joint and several liability
     provisions of the Code relating to employee benefit plans and (vii) except
     claims for benefits payable in the normal operation of such Shire
     Employment Obligations, there are no investigations by any governmental
     agency, termination proceedings or other claims, suits or proceedings
     against or involving any such Shire Employment Obligation or asserting any
     rights to or claims for benefits under any such Shire Employment
     Obligation. In respect of any Shire Employment Obligations benefiting Shire
     UK employees, (i) the only benefits provided are defined contribution
     benefits and no promise, assurance or undertaking has been given to any of
     the employees (whether legally binding or not) as to the provision of
     retirement, death or disability benefits at a particular level and (ii)
     there are not in respect of any retirement benefits scheme or the benefits
     under it any actions, suits or claims pending or threatened (other than
     routine claims or benefits) against the trustees or administrators of that
     scheme or against Shire. Each Shire Employment Obligation of Shire and its
     Subsidiaries (if any) that is intended to be a tax-qualified plan has been
     the subject of a determination letter from the Internal Revenue Service to
     the effect that such Shire Employment Obligation and each related trust is
     qualified and exempt from Federal income taxes under Sections 401(a) and
     501(a), as applicable, respectively, of the Code, no such determination
     letter has been revoked, and revocation has not been threatened and no
     event has occurred and no circumstances exist that would reasonably be
     expected to adversely affect the tax qualification of such Shire Employment
     Obligation. Each of the Shire Employment Obligations with respect to
     employees or former employees employed by Shire or any of its Subsidiaries
     outside of the United States are in compliance in all material respects
     with all applicable law (including, where applicable, Article 141 of the
     Treaty of Rome) and,
<PAGE>

                                      -45-

     to the extent the benefits provided thereunder are not mandated by the laws
     of the applicable jurisdiction, copies of the applicable written plan
     document have been made available to Roberts.

          (r)  Labor Relations.  (i) There is no unfair labor practice
               ---------------
     complaint pending against Shire or any of its Subsidiaries or, to the
     knowledge of Shire, threatened against them before the National Labor
     Relations Board or any other U.S. or non-U.S. governmental or regulatory
     authority, and, to the knowledge of Shire, no grievance or arbitration
     proceeding arising out of or under any of their Shire Employment
     Obligations is so pending against Shire or any of its Subsidiaries or
     threatened against them; (ii) to the knowledge of Shire, there is no basis
     for an unfair labor practice finding against Shire or any of its
     Subsidiaries; (iii) no strike, labor dispute, slowdown or stoppage is
     pending or, to the knowledge of Shire, threatened against Shire or any of
     its Subsidiaries; and (iv) no union has ever represented any employee of
     Shire or any of its Subsidiaries.

          (s)  Intellectual Property Rights.  (i)  Section 3.2(s)(i) of the
               ----------------------------
     Shire Disclosure Schedule sets forth a complete and accurate list
     (including registration numbers and dates of filing, renewal and
     termination, where applicable, for each jurisdiction where filed) of all
     Intellectual Property owned by Shire and its Subsidiaries which is material
     to Shire and its Subsidiaries, taken as a whole ("Shire Intellectual
                                                       ------------------
     Property"), including any Liens thereon, the name of the holder of any such
     --------
     Lien and the amount and nature of any obligation secured by any such Lien.
     All Shire Intellectual Property is owned by Shire or its Subsidiaries free
     and clear of all Liens, no Shire Intellectual Property has been canceled,
     abandoned or otherwise terminated and all patent applications, trademark
     applications and copyright applications included in Shire Intellectual
     Property have been duly filed and are recorded on the public record in the
     name of Shire or one of its Subsidiaries and all renewal fees have been
     duly paid other than where such action would not have a Shire Material
     Adverse Effect.  Neither Shire nor any of its Subsidiaries has granted any
     license or other rights with respect to any Shire Intellectual Property to
     any other person or entity.

             (ii) Shire has no knowledge that any of its or its Subsidiaries'
     granted patents are invalid; to the knowl-
<PAGE>

                                      -46-

     edge of Shire, no Shire Intellectual Property is being infringed by any
     third party in any material respect; and, to the knowledge of Shire, its
     current operations do not infringe a granted patent of a third party in any
     material respect.

             (iii)  Neither Shire nor any of its Subsidiaries has any license or
     other rights with respect to any Intellectual Property owned by any other
     person or entity.

             (iv) All technology, processes, techniques and methods of
     manufacture used in or necessary to the manufacturing or research
     operations of Shire and its Subsidiaries, except to the extent the same are
     in the public domain, are subject to valid and effective confidentiality
     agreements between Shire and its employees, have been memorialized to the
     extent required by good manufacturing practice and, to the knowledge of
     Shire, are the subject of no claim, whether or not asserted, that their use
     or employment by Shire or any of its Subsidiaries violates the rights of
     any person.

          (t)  Insurance.  Section 3.2(t) of the Shire Disclosure Schedule sets
               ---------
     forth (i) a complete and accurate list of all policies of insurance of
     Shire and its Subsidiaries currently in force, including surety bonds or
     other credit support therefor (the "Shire Insurance Policies"), the current
                                         ------------------------
     annual premiums for each Shire Insurance Policy, the types of risk covered
     and limits of coverage and (ii) a description of claims experience of Shire
     (x) in the twelve months immediately preceding the date hereof with respect
     to all matters and (y) since its incorporation with respect to product
     liability matters, matters arising by reason of clinical trials,
     environmental matters and workmen's compensation.  All Shire Insurance
     Policies are in full force and effect and all premiums due thereon have
     been paid.  Shire has complied in all material respects with the terms and
     provisions of the Shire Insurance Policies.  Shire has never applied for
     and been refused or denied any policy of insurance with respect to product
     liability matters, matters arising by reason of clinical trials,
     environmental matters and workmen's compensation.  Shire's insurance
     coverage is adequate in kind and amount based on current industry practice.

          (u)  Books and Records.  (i)  The books of account and other
               -----------------
     financial records of Shire and its Subsidiaries that have been made
     available to Roberts prior to the date
<PAGE>

                                      -47-

     hereof or are made available thereafter are or will be true, complete and
     correct in all material respects and do not, and will not, contain any
     omissions which, in light of the circumstances in which they are made, are
     materially misleading.

             (ii) The minute books and other records of Shire and its
     Subsidiaries that have been or will be made available to Roberts contain
     records of all meetings of Shire and its Subsidiaries prior to the date
     hereof and prior to the Effective Time, respectively, are or will be
     accurate in all material respects and reflect accurately in all material
     respects all other corporate action of the shareholders and directors and
     any committees of the Board of Directors of Shire and its Subsidiaries.

          (v)  Undisclosed Liabilities.  Except as set forth in the Public UK
               -----------------------
     Documents and except for liabilities and obligations incurred in the
     ordinary course of business consistent with past practice and UK GAAP
     neither Shire nor any of its Subsidiaries has any liabilities or
     obligations of any nature (whether accrued, absolute, contingent or
     otherwise) required by UK GAAP to be set forth on a consolidated balance
     sheet of Shire and its consolidated Subsidiaries or in the notes thereto
     and which, individually or in the aggregate, could reasonably be expected
     to have a Shire Material Adverse Effect.

          (w)  FDA, DEA Matters.  Section 3.2(w) of the Shire Disclosure
               ----------------
     Schedule sets forth a complete and accurate list of (i) each
     investigational new drug filing made by Shire or any of its Subsidiaries
     with the FDA or any non-U.S. equivalents (including, without limitation,
     the MCA), (ii) each clinical trial protocol submitted by Shire or any of
     its Subsidiaries to the FDA or any non-U.S. equivalents, (iii) each new
     drug application and abbreviated or supplemental new drug application filed
     by Shire or any of its Subsidiaries pursuant to the Federal Food, Drug and
     Cosmetic Act, as amended, or any non-U.S. equivalents (iv) each product
     license application filed by Shire or any of its Subsidiaries pursuant to
     the Public Health Service Act, as amended, or any non-U.S. equivalents and
     (v) each establishment license application filed with respect to any
     product of Shire or any of its Subsidiaries under the Public Health Service
     Act, as amended or any non-U.S. equivalents.  (i) There are no lawsuits,
     arbitrations, legal or administrative or regulatory proceedings, charges,
     complaints or investigations by the FDA, the DEA, the DOJ
<PAGE>

                                      -48-

     or any state or non-U.S. regulatory agency pending or, to the best
     knowledge of Shire, threatened against or relating to Shire, any of its
     Subsidiaries or any of their respective products, (ii) there have been no
     product recalls or similar actions by Shire or any of its Subsidiaries,
     (iii) each clinical trial with respect to products of Shire and its
     Subsidiaries has been conducted in accordance with its clinical trial
     protocol and applicable regulations and Shire or one of its Subsidiaries
     has filed all required notices (and made available to Roberts copies
     thereof) of adverse drug experiences, injuries or deaths relating to
     clinical trials of such products, and Shire or one of its Subsidiaries has
     filed all required notices of any such occurrence, (iv) to the best
     knowledge of Shire, all clinical trials have been and are being conducted
     in substantial compliance with all applicable good clinical practice
     regulations, (v) neither Shire nor any of its Subsidiaries nor, to the best
     knowledge of Shire, any of their respective officers, employees or agents
     has made an untrue statement of material fact or fraudulent statement to
     the FDA, the MCA, the DEA or other regulatory agencies, failed to disclose
     a material fact required to be disclosed to any of them or committed an
     act, made a statement or failed to make a statement that could reasonably
     be expected to provide a basis for any of them to invoke the policy
     respecting "Fraud, Untrue Statements of Material Facts, Bribery and Illegal
     Gratuities" set forth in 56 Fed. Reg. 46191 (September 10, 1991) or
     equivalent regulations, (vi) there are no unresolved reports, warning
     letters or other documents received from or issued by the FDA, the MCA, the
     DEA or other regulatory agencies that indicate or suggest material lack of
     compliance with FDA or DEA regulatory requirements by Shire, any of its
     Subsidiaries or persons providing services for the benefit of any of them,
     (vii) to the best knowledge of Shire, no person has filed a claim for loss
     or potential loss under any indemnity covering participants in clinical
     trials of products of Shire and its Subsidiaries, (viii) to Shire's
     knowledge, no material modifications to the process by which products of
     Shire or any of its Subsidiaries that have been or are being used in
     clinical trials are manufactured will be necessary in order to manufacture
     commercial quantities of such products, (ix) as to each drug of Shire or
     one of its Subsidiaries for which a new drug application or abbreviated new
     drug application has been approved by the FDA or other regulatory agencies,
     the applicant and all persons performing operations covered by the
     application are in substantial compliance with 21 U.S.C.
<PAGE>

                                      -49-

     Section 355 or 357, 21 C.F.R. Part 314 or 430 et seq. (or any non-U.S.
                                                   ------
     equivalents), respectively, and all terms and conditions of the
     application, (x) Shire and its Subsidiaries are in compliance with all
     applicable registration and listing requirements set forth in 21 U.S.C.
     Section 360 and 21 C.F.R. Part 207 and, to the extent required, Shire and
     its Subsidiaries have obtained licenses from the DEA and are in compliance
     with all such licenses and all applicable regulations promulgated by the
     DEA, (xi) all manufacturing operations conducted by or, to the knowledge of
     Shire, for the benefit of Shire and its Subsidiaries have been and are
     being conducted in compliance with applicable good manufacturing practice
     regulations including those set forth in 21 C.F.R. Parts 210 and 211, (xii)
     neither Shire nor any of its Subsidiaries has received any written notice
     that the FDA, the MCA, the DEA or other regulatory agencies has commenced,
     or threatened to initiate, any action to withdraw its approval or request
     the recall of any product of Shire or its Subsidiaries or withdraw
     advertising or sales promotion materials or commenced, or threatened to
     initiate, any action to enjoin production at any facility owned or used by
     Shire or any of its Subsidiaries or any of their manufacturing locations,
     (xiii) as to each article of drug or consumer product currently
     manufactured and/or distributed by or on behalf of Shire or its
     Subsidiaries, such article is not adulterated or misbranded within the
     meaning of the FDCA, 21 U.S.C. Sections 301 et seq., and all advertising
                                                 ------
     and sales promotional materials of Shire or its Subsidiaries are otherwise
     in conformance with applicable regulations and (iv) neither Shire nor any
     of its Subsidiaries nor, to the knowledge of Shire, any of their respective
     officers, employees, agents or affiliates has been convicted of any crime
     or engaged in any conduct for which debarment is mandated by 21 U.S.C.
     Section 335(a) or authorized by 21 U.S.C. Section 335a(b). To the knowledge
     of Shire, Shire's contractors are in compliance with all applicable law and
     regulations and in respect of the FDA and DEA have secured all licenses,
     renewals and quotas necessary to their operation.

          Shire has made available to Roberts copies of all written
     communications to or from the FDA and the DEA relating specifically to
     Shire, its Subsidiaries and their respective operations or business.

          (x)  Environmental Matters.  (i)  Each of Shire and its Subsidiaries
               ---------------------
     possesses all Environmental Permits re-
<PAGE>

                                      -50-

     quired under applicable Environmental Laws to conduct its business as
     currently conducted and to own and operate its assets, and is in compliance
     in all material respects with the terms and conditions of such
     Environmental Permits.

             (ii) The execution, delivery and performance of this Agreement and
     the consummation of the transactions contemplated hereby will not affect
     the validity or require the transfer of any Environmental Permits held by
     Shire or its Subsidiaries, and will not require any notification,
     disclosure, registration, reporting, filing, investigation or redemption
     under any Environmental Law.

             (iii)  Each of Shire and its Subsidiaries is in compliance in all
     material respects with all applicable Environmental Laws and has no
     material liability under any Environmental Law.

             (iv) There is no civil, criminal or administrative action, suit,
     demand, claim, hearing, notice of violation, proceeding, notice or demand
     letter, or request for information pending or, to the knowledge of Shire
     threatened, under any Environmental Law (x) against Shire or its
     Subsidiaries or (y) to the knowledge of Shire against any person or entity
     in connection with which liability could reasonably be expected to be
     imputed or attributed by law or contract to Shire or its Subsidiaries.

             (v) No property or facility presently or formerly owned, leased or
     operated by Shire or its Subsidiaries, and no property or facility at which
     Hazardous Materials of Shire or its Subsidiaries have been stored, treated
     or disposed of or at which any Hazardous Materials have been manufactured,
     handled, tested, formulated, prepared, encapsulated, packaged, bottled, or
     stored for Shire or its Subsidiaries ("Shire Product Sites") is listed or
                                            -------------------
     proposed for listing on the National Priorities List or the Comprehensive
     Environmental Response, Compensation and Liability Information System, both
     promulgated under CERCLA, or on any comparable list established under any
     Environmental Law.

             (vi) There has been no disposal, spill, discharge, emission or
     release of any Hazardous Material by Shire or its Subsidiaries on, at,
     under or from any property presently or formerly owned, leased or operated
     by Shire or its Subsidiaries and there are no Hazardous Materials located
     in, at, on or under any such facility or property,
<PAGE>

                                      -51-

     or, to the knowledge of Roberts, at any Shire Product Site or other
     location where Hazardous Materials of Shire or any of its Subsidiaries have
     been stored, treated or disposed of (a "Shire Third Party Site"), in each
                                             ----------------------
     case that could reasonably be expected to result in the incurrence of any
     material liability, by Shire or its Subsidiaries under any Environmental
     Law.

             (vii)  There are no underground storage tank or other underground
     storage receptacles or related piping, or any impoundments containing
     Hazardous Materials located on any facility or property owned, leased or
     operated by Shire or any of its Subsidiaries.

             (viii)  No Lien has been recorded against any properties, assets or
     facilities owned, leased or operated by Shire or any of its Subsidiaries
     under any Environmental Law.

             (ix) Neither Shire nor any of its Subsidiaries is obligated to
     perform any investigation or other action under any Environmental Law
     pursuant to any order, decree, judgment or agreement by which it is bound,
     or has assumed by contract or agreement any obligation or liability under
     any Environmental Law.

          Shire has made available to Roberts all material records and files,
     including, but not limited to, all assessments, reports, studies, audits,
     analyses, tests and data, in possession, custody or control of Shire or its
     Subsidiaries concerning compliance by Shire and its Subsidiaries with, or
     liability under, any Environmental Law, including, without limitation,
     those concerning the existence of Hazardous Materials at facilities or
     properties currently or formerly owned, operated or leased by Shire or its
     Subsidiaries or at any Shire Product Site or Shire Third Party Site.

          (y)  Products.  Each of the products produced or sold by Shire and
               --------
     its Subsidiaries:  (i) is, and at all times up to and including the date
     hereof has been, in compliance in all material respects with all applicable
     U.K. and non-U.K. laws and regulations; (ii) is, and at all relevant times
     has been, fit for the ordinary purposes for which it is intended to be used
     and conforms in all material respects to any promises or affirmations of
     fact made on the container, label or promotional materials for such product
     or in connection with its sale; and (iii) contains
<PAGE>

                                      -52-

     no design or manufacturing defect. Neither Shire nor any of its
     Subsidiaries has received notice of any product warranty claims. Neither
     Shire nor any of its Subsidiaries is aware of any facts which are
     reasonably likely to cause (i) the withdrawal or recall of any product sold
     or intended to be sold by Shire or its Subsidiaries, (ii) a change in the
     marketing classification, labeling or promotional materials of any such
     products, or (iii) a termination or suspension of marketing of any such
     products. There are no material claims pending or, to the knowledge of
     Shire, threatened against Shire or its Subsidiaries with respect to the
     quality of or absence of defects in such products nor are there any facts
     known to Shire relating to the quality of or absence of defects in such
     products which, if known by a potential claimant or governmental authority,
     could reasonably be expected to give rise to a claim or proceeding. To the
     knowledge of Shire, no supplier of a raw material required for a material
     product of Shire and the Subsidiaries for which there is not a permissible
     replacement obtainable under commercially reasonable terms, has indicated
     that it will not continue to supply such raw materials on terms consistent
     with those on the date hereof.

          (z)  Marketing Practices.  Shire's operations and commercial conduct
               -------------------
     and those of its Subsidiaries have at all times conformed in all material
     respects to the Code of Marketing Practices of the Pharmaceutical Research
     Industry Association.

          (aa)  Ordinary Shares.  As of the Effective Time, the Ordinary Shares
                ---------------
     comprising the Merger Consideration (including Ordinary Shares delivered to
     the Depositary underlying the Shire ADSs constituting Merger Consideration)
     will have been duly authorized for issuance and, when issued and delivered
     in accordance with the terms of this Agreement, will be validly issued and
     fully paid.

          (bb)  Pooling.  Neither Shire nor any of its Affiliates has taken or
                -------
     agreed to take any action or failed to take any action that would prevent
     the Merger from being treated for financial accounting purposes as a
     "pooling of interests" in accordance with US GAAP and the regulations and
     interpretations of the SEC.

          (cc)  Merger Consideration.  As of the Effective Time, the Shire ADSs
                --------------------
     and Ordinary Shares received by the Holders as Merger Consideration will
     represent less than
<PAGE>

                                      -53-

     fifty percent of both the total voting power and the total value of the
     outstanding stock of Shire within the contemplation of Treas. Reg. (S)
     1.367(a)-3(c)(1)(i).

          (dd)  Active Trade or Business.  Shire, a "qualified subsidiary" (as
                ------------------------
     defined in Treas. Reg. (S) 1.367(a)-3(c)(5)(vii)) of Shire or a "qualified
     partnership" (as defined in Treas. Reg. (S) 1.367(a)-3(c)(5)(viii)) of
     which Shire is a partner will, as of the Effective Time, have been engaged
     in an active trade or business outside the United States for the entire 36-
     month period immediately before the Effective Time, within the meaning of
     and as contemplated by Treas. Reg. (S) 1.367(a)-3(c)(3).  None of Shire,
     any qualified subsidiary of Shire or any qualified partnership of which
     Shire is a partner has, nor will have as of the Effective Time, any
     intention to dispose of or discontinue any trade or business referred to in
     the previous sentence if doing so would cause the active trade or business
     test of Treas. Reg. (S) 1.367(a)-3(c)(3) not to be satisfied.

          (ee)  Asset Acquisitions.  As of the Effective Time, none of Shire,
                ------------------
     any qualified subsidiary of Shire or any qualified partnership of which
     Shire is a partner (each as defined above in Section 3.2(dd)) will own any
     assets acquired outside the ordinary course of business within the
     preceding 36-month period that would cause Shire to fail to satisfy the
     "substantiality test" set forth in Treas. Reg. (S) 1.367(a)-3(c)(3)(iii).

          (ff)  Ownership of Roberts Shares.  Except as contemplated in this
                ---------------------------
     Agreement and the Option Agreement as of the date hereof and the Effective
     Time, none of Shire, any of its Subsidiaries or, to Shire's knowledge, any
     of its "affiliates" or "associates" (as such terms are defined in the
     Shareholder Protection Act), (i) owns, or during the five-year period prior
     to the date hereof owned, or has any rights to acquire or vote any shares
     of Common Stock or (ii) has any agreement, arrangement or understanding for
     the purpose of acquiring, holding, voting or disposing of Common Stock with
     any other person that beneficially owns, or whose affiliates or associates
     beneficially own, Common Stock.
<PAGE>

                                      -54-

                                   ARTICLE IV


                              COVENANTS OF ROBERTS

          4.1.  Regular Course of Business.  Except in connection with the
                --------------------------
performance by Roberts of its obligations under the Agreement, until the
Effective Time, Roberts shall conduct its and its Subsidiaries' business only in
the ordinary course and shall use reasonable efforts to maintain and preserve
its business organization, assets, employees and business relationships and to
maintain all of its material properties and assets in useful and good condition,
ordinary wear and tear excepted.

          4.2.  Certain Prohibited Activities.  Until the Effective Time,
                -----------------------------
except as contemplated by this Agreement or as set forth on Section 4.2 of the
Roberts Disclosure Schedule, Roberts shall not, and shall not permit any of its
Subsidiaries to, without the prior written consent of Shire:  (a) cease to be a
corporation duly organized, validly existing and in good standing under the laws
of its jurisdiction of incorporation, or in good standing as a foreign
corporation in any jurisdiction where the character of its assets or nature of
its business makes such qualification necessary; (b) authorize or issue any
additional shares of its capital stock, any Equity Equivalents, any debt
securities or other evidence of its indebtedness or any SARs; (c) repay any of
its Indebtedness prior to scheduled maturity (other than in the ordinary course
of business) or redeem or otherwise acquire any of its capital stock or any
Equity Equivalents or make any payment with respect to any of the foregoing
(other than regular, periodic payments of interest made with respect to any
Indebtedness); (d) split, combine or reclassify any of its capital stock or
declare, set aside or pay any dividend or other distribution in respect of any
of its capital stock; (e) acquire any stock, partnership or other equity
interest in or any equity or debt security of any other person or entity; (f)
amend its Certificate of Incorporation or By-Laws (or equivalent charter
documents); (g) violate or fail to comply in any material respect with any
statute, law, ordinance, regulation, rule, order or other legal requirement of
any government, authority or any other governmental department or agency, or any
judgment, decree or order of any court or governmental body or agency applicable
to its business or operations (other than any violations or failures to comply
which could not reasonably be expected, individually or in the aggregate, to
have a Roberts Material Adverse Effect); (h) enter into any contract, agreement
or other commitment with any
<PAGE>

                                      -55-

present or former director, officer or securityholder of Roberts or any person
or entity controlled by any such person other than in the ordinary course of
business and where the amount involved is not in excess of $500,000; (i) acquire
or dispose of any material real property or any material leasehold interest in
real property, or create or suffer to exist any Lien on any material assets
owned or leased by it; (j) fail to comply in all material respects with all of
its obligations with respect to all material Permits or voluntarily take or omit
to take any action which could reasonably be expected to result in the
revocation, nonrenewal, modification, suspension or termination of any such
Permit (other than any violations or failures to comply which could not
reasonably be expected, individually or in the aggregate, to have a Roberts
Material Adverse Effect); (k) (i) grant to any officer of Roberts or any of its
Subsidiaries any increase in compensation, (ii) grant to any employee of Roberts
or any of its Subsidiaries any increase in severance or termination pay, (iii)
enter into any employment, severance or termination agreement with any employee
of Roberts or any of its Subsidiaries or (iv) enter into any Employment
Obligation, or permit the modification or termination of any existing Employment
Obligation; (l) dispose of, permit to lapse, modify, terminate, grant any
interest to any person or entity in, or create or suffer to exist any Lien on or
with respect to, any Roberts Intellectual Property; (m) take any action that
would cause it to fail to maintain in full force and effect, comply in all
material respects with all of the terms and provisions of or pay all premiums
due on any Insurance Policy; (n) enter into any material agreement or permit the
modification or termination of any material agreement outside the ordinary
course of business; (o) merge or consolidate with any other person or entity or
acquire control of or purchase all or substantially all of the assets of any
other person or entity; (p) voluntarily incur or permit the incurrence of any
liability not in the ordinary course of business and in excess of $1,000,000;
(q) adopt a plan of complete or partial liquidation; or (r) undertake any action
which would jeopardize accounting for the Merger as a pooling of interests.

          4.3.  Notice of Certain Events.  Roberts will give notice to Shire,
                ------------------------
promptly after obtaining knowledge thereof, of (i) any representation or
warranty made by it contained in this Agreement that is qualified as to
materiality becoming untrue or inaccurate in any respect or any such
representation or warranty that is not so qualified becoming untrue or
inaccurate in any material respect or (ii) the failure by it to comply with or
satisfy in any material respect any covenant, condition or
<PAGE>

                                      -56-

agreement to be complied with or satisfied by it under this Agreement.

          4.4.  Access.  Roberts shall afford the officers, employees and
                ------
representatives of Shire, and its counsel and auditors, reasonable access during
normal business hours prior to the Effective Time to its facilities, properties,
equipment, files, accounts, books and records so that Shire may have full
opportunity to make such investigations as it may desire to make of the affairs
of Roberts.  Shire will hold, and will cause its respective officers, employees,
accountants, counsel, financial advisers and other representatives and
affiliates to hold, any confidential information in accordance with the terms of
that certain Confidentiality Agreement dated as of June 1, 1999, between Shire
and Roberts.

          4.5.  Approvals.  Roberts shall use all reasonable efforts to take
                ---------
or cause to be taken all action, and to do or cause to be done all things
reasonably necessary, proper or advisable in order to fulfill and perform its
obligations under this Agreement or otherwise consummate and make effective the
transactions contemplated hereby.  Roberts shall use all commercially reasonable
efforts to obtain or cause to be obtained all Roberts Governmental Approvals and
Roberts Third Party Approvals.

          4.6.  No Solicitation.  (a) Prior to the Effective Time, Roberts
                ---------------
agrees that neither it, any of its Subsidiaries, nor any of their respective
directors, officers, employees, agents or representatives of the foregoing,
will, directly or indirectly, (i) solicit or initiate (including by way of
furnishing or disclosing non-public information) any inquiries or the making of
any proposal with respect to any merger, consolidation or other business
combination involving Roberts or the acquisition of all or any significant part
of the assets or capital stock of Roberts (a "Roberts Acquisition Transaction")
                                              -------------------------------
or (ii) negotiate, explore or otherwise engage in discussions with any person
(other than Shire and its representatives) with respect to any Roberts
Acquisition Transaction, or which may reasonably be expected to lead to a
proposal for a Roberts Acquisition Transaction or enter into any agreement,
arrangement or understanding with respect to any such Roberts Acquisition
Transaction or which would require it to abandon, terminate or fail to
consummate the Merger or any other transaction contemplated by this Agreement;
provided, however, that Roberts may, in response to an unsolicited written
- --------  -------
proposal from a third party regarding a Roberts Superior Proposal (as
hereinafter defined), furnish information to, negotiate or otherwise engage
<PAGE>

                                      -57-

in discussions with such third party, if the Board of Directors of Roberts
determines in good faith, after consultation with its financial advisors and
based upon advice of outside counsel that such action is required for the Board
of Directors to comply with its fiduciary duties under applicable law.

          (b)  Except as may be required pursuant to the fiduciary duties of
Roberts' Board of Directors under applicable law, Roberts agrees that, as of the
date hereof, it and its Subsidiaries, and the respective directors, officers,
employees, agents and representatives of the foregoing, shall immediately cease
and cause to be terminated any existing activities, discussions or negotiations
with any person (other than Shire and its representatives) conducted heretofore
with respect to any Roberts Acquisition Transaction.  Roberts agrees to promptly
advise Shire of any inquiries or proposals received by, any such information
requested from, or any negotiations or discussions sought to be initiated or
continued with, Roberts or its Subsidiaries, or any of the respective directors,
officers, employees, agents or representatives of the foregoing, in each case
from a person (other than Shire and its representatives) with respect to a
Roberts Acquisition Transaction, and the terms hereof, including the identity of
such third party and the general terms of any financing arrangement or
commitment in connection with such Roberts Acquisition Transaction, and, except
as may otherwise be required pursuant to the fiduciary duties of Roberts' Board
of Directors under applicable law, to update on an ongoing basis or upon Shire's
reasonable request, the status thereof, as well as any actions taken or other
developments pursuant to this Section 4.6.  As used herein, "Roberts Superior
                                                             ----------------
Proposal" means a bona fide, written and unsolicited proposal or offer made by
- --------
any persons (or group) (other than Shire or any of its Subsidiaries) with
respect to a Roberts Acquisition Transaction (i) on terms which the Board of
Directors of Roberts determines in good faith, and in the exercise of reasonable
judgment (based on the advice of independent financial advisors and legal
counsel), to be more favorable to Roberts and its shareholders than the
transactions contemplated hereby (including taking into account the financing
thereof.)

          4.7.  Pooling of Interests.  Roberts shall use all reasonable
                --------------------
efforts to cause the Merger to be accounted for as a "pooling of interests" in
accordance with US GAAP, Accounting Principles Board Opinion 16 and applicable
SEC rules, regulations and policies and shall take no action that would cause
such accounting treatment not to be obtained.
<PAGE>

                                      -58-

          4.8.  ISRA.  Roberts shall obtain from the New Jersey Department of
                ----
Environmental Protection either (i) a declaration of non-applicability of the
New Jersey Industrial Site Recovery Act ("ISRA") to the Merger or any other
                                          ----
transactions contemplated thereby, or (ii) approval of a negative declaration or
other action required to comply with ISRA, in each case which is reasonably
acceptable to Shire.

                                   ARTICLE V


                     COVENANTS OF SHIRE AND ACQUISITION SUB

          5.1.  Regular Course of Business.  Except in connection with the
                --------------------------
performance by Shire and Acquisition Sub of their respective obligations under
this Agreement, until the Effective Time, Shire shall conduct its and its
Subsidiaries' business only in the ordinary course and shall use reasonable
efforts to maintain and preserve its business organization, assets, employees
and business relationships and to maintain all of its material properties and
assets in useful and good condition, ordinary wear and tear excepted.

          5.2.  Certain Prohibited Activities.  Until the Effective Time,
                -----------------------------
except as contemplated by this Agreement or as set forth on Section 5.2 of the
Shire Disclosure Schedule, Shire shall not, and shall not permit any of its
Subsidiaries to, without the prior written consent of Roberts:  (a) cease to be
a corporation duly organized, validly existing and, where applicable, in good
standing under its jurisdiction of incorporation, or in good standing as a
foreign corporation in any applicable jurisdiction where the character of its
assets or nature of its business makes such qualification necessary; (b)
authorize or issue any additional shares of its capital stock, any Equity
Equivalents, any debt securities or other evidence of its indebtedness or any
SARs; (c) repay any of its Indebtedness prior to scheduled maturity (other than
in the ordinary course of business) or redeem or otherwise acquire any of its
capital stock or any Equity Equivalents or make any payment with respect to any
of the foregoing (other than regular, periodic payments of interest made with
respect to any Indebtedness); (d) split, combine or reclassify any of its
capital stock or declare, set aside or pay any dividend or other distribution in
respect of any of its capital stock; (e) acquire any stock, partnership or other
equity interest in or any equity or debt security of any other person or entity;
(f) amend its Memorandum and Articles of Association (or equivalent char-
<PAGE>

                                      -59-

ter documents); (g) violate or fail to comply in any material respect with any
statute, law, ordinance, regulation, rule, order or other legal requirement of
any government, authority or any other governmental department or agency, or any
judgment, decree or order of any court or governmental body or agency applicable
to its business or operations (other than any violations or failures to comply
which could not reasonably be expected, individually or in the aggregate, to
have a Shire Material Adverse Effect); (h) enter into any contract, agreement or
other commitment with any present or former director, officer or securityholder
of Shire or any person or entity controlled by any such person other than in the
ordinary course of business and where the amount involved is not in excess of
$500,000; (i) fail to comply in all material respects with all of its
obligations with respect to all material Permits or voluntarily take or omit to
take any action which could reasonably be expected to result in the revocation,
nonrenewal, modification, suspension or termination of any such Permit (other
than any violations or failures to comply which could not reasonably be
expected, individually or in the aggregate, to have a Shire Material Adverse
Effect); (j) (i) grant to any officer of Shire or any of its Subsidiaries any
increase in compensation, (ii) grant to any employee of Shire or any of its
Subsidiaries any increase in severance or termination pay, (iii) enter into any
employment, severance or termination agreement with any employee of Shire or any
of its Subsidiaries or (iv) enter into any Employment Obligation or permit the
modification or termination of any existing Employment Obligation; (k) dispose
of, permit to lapse, modify, terminate, grant any interest to any person or
entity in, or create or suffer to exist any Lien with respect to, any Shire
Intellectual Property; (l) take any action that would cause it to fail to
maintain in full force and effect, comply in all material respects with all of
the terms and provisions of or pay all premiums due on any Insurance Policy; (m)
enter into any material agreement or permit the modification of any material
agreement outside the ordinary course of business; (n) merge or consolidate with
any other person or entity or acquire control of or purchase all or
substantially all of the assets of any other person or entity; (o) voluntarily
incur or permit the incurrence of any liability not in the ordinary course of
business and in excess of $1,000,000; (p) adopt a plan of complete or partial
liquidation; or (q) undertake any actions which would jeopardize accounting for
the Merger as a pooling of interests.

          5.3.  Notice of Certain Events.  Each of Shire and Acquisition Sub
                ------------------------
will give notice to Roberts promptly after obtaining knowledge thereof, of (i)
any representation or war-
<PAGE>

                                      -60-

ranty made by it contained in this Agreement that is qualified as to materiality
becoming untrue or inaccurate in any respect or any such representation or
warranty that is not so qualified becoming untrue or inaccurate in any material
respect or (ii) the failure by it to comply with or satisfy in any material
respect any covenant, condition or agreement to be complied with or satisfied by
it under this Agreement.

          5.4.  Access.  Shire and Acquisition Sub shall afford the officers,
                ------
employees and representatives of Roberts, and its counsel and auditors,
reasonable access during normal business hours during the period prior to the
Effective Time to their respective facilities, properties, equipment, files,
accounts, books and records so that Roberts may have full opportunity to make
such investigations as it may desire to make of the affairs of Shire and
Acquisition Sub.  Roberts will hold, and will cause its respective officers,
employees, accountants, counsel, financial advisers, and other representatives
and affiliates to hold, any confidential information in accordance with the
terms of that certain Confidentiality Agreement dated as of June 1, 1999,
between Shire and Roberts.

          5.5.  Approvals.  Each of Shire and Acquisition Sub shall use all
                ---------
reasonable efforts to take or cause to be taken all actions, and to do or cause
to be done all things, reasonably necessary, proper or advisable in order to
fulfill and perform its obligations under this Agreement or otherwise consummate
or make effective the transactions contemplated hereby.  Each of Shire and
Acquisition Sub shall use all commercially reasonable efforts to obtain all
Shire Governmental Approvals and Shire Third Party Approvals.

          5.6.  No Solicitation.  (a)  Prior to the Effective Time, Shire
                ---------------
agrees that neither it, any of its Subsidiaries, nor any of their respective
directors, officers, employees, agents or representatives of the foregoing,
will, directly or indirectly, (i) solicit or initiate (including by way of
furnishing or disclosing non-public information) any inquiries or the making of
any proposal with respect to any merger, consolidation or other business
combination involving Shire or the acquisition of all or any significant part of
the assets or capital stock of Shire (a "Shire Acquisition Transaction") or (ii)
                                         -----------------------------
negotiate, explore or otherwise engage in discussions with any person (other
than Roberts and its representatives) with respect to any Shire Acquisition
Trans-
<PAGE>

                                      -61-

action, or which may reasonably be expected to lead to a proposal for a
Shire Acquisition Transaction or enter into any agreement, arrangement or
understanding with respect to any such Shire Acquisition Transaction or which
would require it to abandon, terminate or fail to consummate the Merger or any
other transaction contemplated by this Agreement; provided, however, that Shire
                                                  --------  -------
may, in response to an unsolicited written proposal from a third party regarding
a Shire Superior Proposal (as hereinafter defined), furnish information to,
negotiate or otherwise engage in discussions with such third party, if the Board
of Directors of Shire determines in good faith, after consultation with its
financial advisors and based upon advice of outside counsel that such action is
required for the Board of Directors to comply with its fiduciary duties under
applicable law.

          (b)  Except as may be required pursuant to the fiduciary duties of
Shire's Board of Directors under applicable law, Shire agrees that, as of the
date hereof, it and its Subsidiaries, and the respective directors, officers,
employees, agents and representatives of the foregoing, shall immediately cease
and cause to be terminated any existing activities, discussions or negotiations
with any person (other than Roberts and its representatives) conducted
heretofore with respect to any Shire Acquisition Transaction.  Shire agrees to
promptly advise Roberts of any inquiries or proposals received by, any such
information requested from, or any negotiations or discussions sought to be
initiated or continued with, Shire or its Subsidiaries, or any of the respective
directors, officers, employees, agents or representatives of the foregoing, in
each case from a person (other than Shire and its representatives) with respect
to a Shire Acquisition Transaction, and the terms hereof, including the identity
of such third party and the general terms of any financing arrangement or
commitment in connection with such Shire Acquisition Transaction, and, except as
may otherwise be required pursuant to the fiduciary duties of Shire's Board of
Directors under applicable law, to update on an ongoing basis or upon Roberts'
reasonable request, the status thereof, as well as any actions taken or other
developments pursuant to this Section 5.6.  As used herein, "Shire Superior
                                                             --------------
Proposal" means a bona fide, written and unsolicited proposal or offer made by
- --------
any persons (or group) (other than Roberts or any of its Subsidiaries) with
respect to a Shire Acquisition Transaction (i) on terms which the Board of
Directors of Shire determines in good faith, and in the exercise of reasonable
judgment (based on the advice of independent financial advisors and legal
counsel), to be more favorable to Shire and its shareholders than the
transactions contemplated hereby (including taking into account the financing
thereof.)

          5.7.  Pooling of Interests.  Shire shall use all reasonable efforts
                --------------------
to cause the Merger to be accounted for as a
<PAGE>

                                      -62-

"pooling of interests" in accordance with US GAAP, Accounting Principles Board
Opinion 16 and applicable SEC rules, regulations and policies and shall take no
action that would cause such accounting treatment not to be obtained.

          5.8.  Indemnification.  (a) From and after the Effective Time and
                ---------------
until the sixth anniversary of the Effective Time and for so long thereafter as
any claim for indemnification asserted on or prior to such date has not been
fully adjudicated, Shire and the Surviving Corporation shall indemnify, defend
and hold harmless each individual who is now, or has been at any time prior to
the date hereof or who becomes prior to the Effective Time, a director or
officer of Roberts or any of its Subsidiaries against all losses, claims,
damages, costs, expenses (including attorneys' fees) or liabilities (including
attorneys' fees) arising out of actions or omissions or alleged actions or
omissions occurred at or prior to the Effective Time to the same extent and on
the same terms and conditions (including with respect to advancement of
expenses) permitted or required under applicable law and Roberts' Certificate of
Incorporation and By-Laws in effect at the date hereof.

          (b)  For a period of six years after the Effective Time, Shire and the
Surviving Corporation shall cause to be maintained in effect the current
policies of directors' and officers' liability insurance maintained by Roberts
(provided that the Surviving Corporation may substitute therefor policies of at
least the same coverage and amounts containing terms and conditions which are no
less advantageous to the insured parties) with respect to claims arising from
facts or events which occurred on or before the Effective Time; provided,
                                                                --------
however, that if the premiums with respect to such insurance exceed 150% of the
- -------
annual premiums paid as of the date hereof by Roberts for such insurance, Shire
and the Surviving Corporation shall be obligated to purchase directors' and
officers' liability insurance with the maximum coverage as can be obtained at an
annual premium equal to 150% of the annual premiums paid by Roberts as of the
date hereof.

          (c)  The provisions of this Section are intended to be for the benefit
of, and shall be enforceable by, each indemnified party and each party entitled
to insurance coverage under paragraph (b) above, respectively, and his or her
heirs and legal representatives, and shall be in addition to any other rights an
indemnified party may have under the certificates or articles of incorporation
or by-laws of the Surviving Corporation or any of its Subsidiaries, under the
New Jersey Law or otherwise.
<PAGE>

                                      -63-

                                   ARTICLE VI


                          AGREEMENTS REGARDING OPTIONS

                               AND OTHER BENEFITS

          6.1.  Stock Option Plans.  (a)  At the Effective Time, Roberts shall,
                ------------------
if necessary, have amended (and Shire and the Surviving Corporation shall have
approved and adopted, respectively) each of the Roberts Option Plans to provide
that each of the Options shall be assumed by Shire (or the Surviving
Corporation) and made applicable to the purchase of Ordinary Shares as provided
in this Section 6.1.  Shire shall assume or replace such Options (or fraction
thereof) so that each holder of an Option (an "Optionee") shall have such
                                               --------
Optionee's Option apply to that number of Ordinary Shares (adjusted to the
nearest whole share) equal to the product of (i) the number of all Options of
such Optionee immediately prior to the Effective Time and (ii) the Exchange
Ratio.  The exercise price per share for each Optionee's Options (adjusted to
the nearest pence) assumed or replaced will equal the old exercise price per
share of Common Stock divided by the Exchange Ratio; provided, however, that in
                                                     --------  -------
the case of any Option to which Section 421 of the Code continues to apply by
reason of its qualification under Section 422 of the Code ("incentive stock
                                                            ---------------
options"), the option price, the number of shares purchasable pursuant to such
- -------
option and the terms and conditions of exercise of such option shall be
determined in order to comply with Section 424(a) of the Code and the
regulations promulgated thereunder.  Without limiting the foregoing, the
duration and other terms of each assumed or replaced Option immediately after
the Effective Time (unless otherwise agreed in writing by the Optionee with
respect to a particular Option) shall be the same as the corresponding Options
that were in effect immediately before the Effective Time, except that all
references to Roberts in the Roberts Option Plans (and the corresponding
references in each option agreement documenting each such Option) shall be
deemed to be references to Shire or the Surviving Corporation, as applicable;
provided, however, that the exercise price with respect to each Ordinary Share
- --------  -------
shall not be less than the nominal value of (Pounds)0.05 thereof.  Roberts will
terminate its Employee Stock Purchase Plan prior to the closing and extinguish
all rights thereunder.

          (b)  As soon as practicable after the Effective Time, Shire shall
deliver to each Optionee appropriate notices setting forth such Optionee's
rights pursuant to the Shire Option
<PAGE>

                                      -64-

Plans and the agreements evidencing the grants of such Options shall continue in
effect on the same terms and conditions.

          (c)  Shire shall take all corporate action necessary to reserve for
issuance a sufficient number of Ordinary shares for delivery upon exercise of
Options.  As soon as practicable after the Effective Time, Shire shall file a
registration statement on Form F-3, Form S-8, or another appropriate form, as
the case may be (or any successor form), with respect to the Ordinary Shares
subject to such options and shall use its reasonable best efforts to maintain
the effectiveness of such registration statement or registration statements (and
maintain the current status of the prospectus or prospectuses contained therein)
for so long as such options remain outstanding.

          6.2.  Continuation of Benefits.  During the period from the
                ------------------------
Effective Time until December 31, 2001, Shire shall maintain or cause to be
maintained wages, compensation levels, employee pension and welfare plans for
the benefit of employees and former employees of Roberts and its Subsidiaries,
which are, in the aggregate, equal or greater in value than those wages,
compensation levels and other benefits provided under Roberts' Employment
Obligations that are in effect on the date hereof.  Nothing in this Agreement
shall be construed as limiting in any way the right of Shire after the Effective
Time to terminate the employment of or lay-off any employee of Roberts.

          6.3.  Severance Policy and Other Agreements.  Shire shall honor or
                -------------------------------------
cause to be honored all severance agreements and employment agreements with
Roberts' directors, officers and employees.

          6.4.  1999 Bonus.  Shire will pay, or cause to be paid, bonuses for
                ----------
calendar year 1999 to Roberts' employees participating in Roberts' RPC Incentive
Compensation Program in amounts equal to each such Roberts employee's bonus for
the year, on a basis consistent with past practice, within the target range
established for each employee (but, in the aggregate, not in excess of
U.S.$1,500,000) as determined by the chief executive of Roberts immediately
prior to the Closing Date (all in accordance with the RPC Incentive Compensation
Program set forth in Schedule 6.4 of the Roberts Disclosure Schedule).  Annual
bonus for 1999 for the four senior officers of Roberts who do not participate in
the RPC Incentive Compensation Program shall be as determined by the
Compensation Committee of Roberts' Board of Directors immediately prior to the
Closing Date in a manner which is consistent with past practice based upon
<PAGE>

                                      -65-

performance, and shall be in an aggregate amount not greater than
U.S.$1,000,000.

          6.5.  Waiver of Preexisting Conditions; Credit for Deductibles;
                ---------------------------------------------------------
Service Credit.  Shire will, or will cause the Surviving Corporation to, (i)
- --------------
waive all limitations as to preexisting conditions with respect to participation
and coverage requirements applicable to the employees and former employees of
Roberts and its Subsidiaries under any welfare plan that such employees or
former employees may be eligible to participate in after the Effective Time,
(ii) provide each employee of Roberts and its Subsidiaries with credit for any
co-payments and deductibles paid during the applicable plan year prior to the
Effective Time in satisfying any applicable deductible or out-of-pocket
requirements under any welfare plans that such employees are eligible to
participate in after the Effective Time, and (iii) provide each employee of
Roberts and its Subsidiaries with credit for all service with Roberts and its
affiliates for purposes of vesting and eligibility to participate under each
employee benefit plan, program, or arrangement of the Purchaser or its
affiliates in which such employees are eligible to participate.

                                  ARTICLE VII


                              CONDITIONS PRECEDENT

          7.1.  Conditions to the Obligations of Each Party to Effect the Merger
                ----------------------------------------------------------------
 .  The respective obligations of each of the parties to effect the Merger shall
be subject to the satisfaction or waiver of each of the following conditions at
or prior to the Closing:

          (a)  Shareholder Approvals.  The Roberts Shareholder Approval and
               ---------------------
     Shire Shareholder Approval shall have been obtained.

          (b)  Certain Approvals.  All Roberts Governmental Approvals and Shire
               -----------------
     Governmental Approvals shall have been obtained, satisfied, waived or
     expired, as applicable.

          (c)  No Proceeding or Litigation.  No order, injunction, decree or
               ---------------------------
     judgment of any court or governmental body or agency shall be in effect
     which materially restrains or prohibits the transactions contemplated
     hereby, and no suit, action, investigation, inquiry or proceeding by any
<PAGE>

                                      -66-

     governmental body or agency or legal or administrative proceeding by any
     governmental body or agency shall have been instituted, or threatened in
     writing, which questions the validity or legality of the transactions
     contemplated hereby.

          (d)  Securities Laws.  The Form F-4 filed by Shire and the Form F-6
               ---------------
     filed by the Depositary shall have become effective under the Securities
     Act and Exchange Act, as applicable, and shall not be the subject of any
     stop order or proceedings seeking a stop order, and Shire shall have
     received all state securities or "blue sky" authorizations necessary to
     issue Shire ADRs and Ordinary Shares pursuant to this Agreement.

          7.2.  Additional Conditions to the Obligations of Roberts.  The
                ---------------------------------------------------
obligation of Roberts to effect the Merger is also subject to the satisfaction
or waiver of each of the following conditions at or prior to Closing:

          (a)  Agreements.  Each of Shire and Acquisition Sub shall have
               ----------
     performed or complied in all material respects with each covenant,
     agreement and obligation to be performed or complied with by it hereunder
     on or prior to the Closing Date.

          (b)  Representations and Warranties.  The representations and
               ------------------------------
     warranties of Shire and Acquisition Sub set forth in this Agreement shall
     be true and correct in all material respects (except that where any
     statement in a representation or warranty expressly includes a standard of
     materiality, such statement shall be true and correct in all respects
     giving effect to such standard) at and as of the Closing Date as if made at
     and as of such time or, if made as of a specified date, as of such date.

          (c)  Officer's Certificate.  Roberts shall have received a
               ---------------------
     certificate, dated the Closing Date, of the President or a Vice President
     of Acquisition Sub and of a director of Shire to the effect that the
     conditions specified in paragraphs (a) and (b) above have been fulfilled.

          (d)  Consents from Third Parties.  All Shire Third Party Approvals
               ---------------------------
     shall have been obtained.

          (e)  Listing.  The London Stock Exchange shall have granted admission
               -------
     of the Ordinary Shares comprising the Merger Consideration to the Official
     List, subject only to
<PAGE>

                                      -67-

     allotment; and the allotment of the Ordinary Shares comprising the Merger
     Consideration shall have occurred, subject only to admission becoming
     effective in accordance with paragraph 7.1 of the Listing Rules of LSE.

          (f)  Tax Opinions.  Roberts shall have received an opinion, relying
               ------------
     on appropriate representations, of either Milbank, Tweed, Hadley & McCloy
     LLP, counsel to Roberts, or Cahill Gordon & Reindel, counsel to Shire to
     the effect that the Merger will constitute a reorganization described in
     Code Section 368(a)(1)(A) and Code Section 368(a)(2)(E) and no gain or loss
     will be recognized by Roberts or any Holder except that (i) a Holder who
     receives cash in lieu of fractional Ordinary Shares or Shire ADSs will
     recognize capital gain or capital loss equal to the difference between the
     cash received and the basis of the Holder's shares of Common Stock
     allocated to the fractional interest and (ii) any Holder required to enter
     into a "gain recognition agreement" within the meaning of Treas. Reg. (S)
     1.367(a)-3(c)(1)(iii)(B) must do so in order to avoid immediate gain
     recognition and may be required to recognize gain at the time and in the
     amount specified in the gain recognition agreement, which opinion shall be
     dated on or about the date that is two business days prior to the date the
     Proxy Statement is first mailed to stockholders of Roberts, shall not have
     been withdrawn or modified in any material respect.

          (g)  Pooling Letter.  There shall have been delivered to Roberts a
               --------------
     letter from its independent auditors, dated as of the Closing Date and
     addressed to Roberts, reasonably satisfactory in form and substance to
     Roberts, setting forth the concurrence of Roberts' independent auditors
     with the conclusion of Roberts' management that it will be appropriate to
     account for the Merger as a "pooling of interests" under US GAAP,
     Accounting Principles Board Opinion No. 16 and all rules, regulations and
     policies of the SEC, if the Merger is consummated in accordance with this
     Agreement.

          (h)  Nasdaq.  The Shire ADSs to be issued in the Merger and under the
               ------
     Roberts Option Plans after the Merger in accordance with this Agreement
     shall have been approved for listing on the Nasdaq National Market.

          7.3.  Additional Conditions to the Obligations of Shire and
                -----------------------------------------------------
Acquisition Sub. The obligations of Shire and Acquisition Sub to effect the
- ---------------
Merger are also subject to the satis-
<PAGE>

                                      -68-

faction or waiver of each of the following conditions at or prior to the
Closing:

          (a)  Agreements.  Roberts shall have performed each covenant,
               ----------
     agreement and obligation to be performed or complied with by it hereunder
     on or prior to the Closing Date.

          (b)  Representations and Warranties.  The representations and
               ------------------------------
     warranties of Roberts set forth in this Agreement shall be true and correct
     in all material respects (except that where any statement in a
     representation or warranty expressly includes a standard of materiality,
     such statement shall be true and correct in all respects giving effect to
     such standard) at and as of the Closing Date as if made at and as of such
     time or, if made as of a specified date, as of such date.

          (c)  Roberts Officer's Certificate.  Shire shall have received a
               -----------------------------
     certificate, dated the date of the Closing, of the President or Vice
     President of Roberts to the effect that the conditions specified in
     paragraphs (a) and (b) above have been fulfilled.

          (d)  Pooling Letter.  There shall have been delivered to Shire a
               --------------
     letter from its independent auditors, dated as of the Closing Date and
     addressed to Shire, reasonably satisfactory in form and substance to Shire,
     setting forth the concurrence of Shire's independent auditors with the
     conclusion of Shire's management that it will be appropriate to account for
     the Merger as a "pooling of interests" under US GAAP, Accounting Principles
     Board Opinion No. 16 and all rules, regulations and policies of the SEC, if
     the Merger is consummated in accordance with this Agreement.

                                  ARTICLE VIII


                                OTHER AGREEMENTS

          8.1.  Preparation of Form F-4, Form F-6, the Proxy Statement and the
                --------------------------------------------------------------
UK Disclosure Document.  As soon as practicable following the date of this
- ----------------------
Agreement, Roberts shall, in cooperation with Shire, prepare and file with the
SEC the Proxy Statement and Shire shall, in cooperation with Roberts, prepare
and file with the SEC the Form F-4, in which the Proxy Statement will be
included as a prospectus.  Each of Roberts and
<PAGE>

                                      -69-

Shire shall use its best efforts to have the Form F-4 declared effective under
the Securities Act as promptly as practicable after such filing. Shire shall
also, as promptly as practicable, use its best efforts to cause the Depositary
to file with the SEC a registration statement on Form F-6 (the "Form F-6") with
                                                                --------
respect to Shire ADRs under the Securities Act and use its best efforts to have
the Form F-6 declared effective as soon as practicable. Shire shall also take
any action (other than qualifying to do business in any jurisdiction in which it
is not now so qualified) required to be taken under any applicable United States
state securities laws in connection with the issuance of Shire ADRs and Ordinary
Shares in the Merger and Shire Ordinary Shares under the Roberts Stock Plans and
Roberts shall furnish all information concerning Roberts and the holders of
Common Stock as may be reasonably requested in connection with any such action.

          8.2.  Roberts Shareholders Meeting.  Roberts shall, as soon as
                ----------------------------
practicable following the date of this Agreement, duly call, give notice of,
convene and hold a meeting of its shareholders (the "Roberts Shareholders
                                                     --------------------
Meeting") for the purpose of obtaining the Roberts Shareholder Approval.  Except
- -------
as required to comply with the fiduciary duties of the Board of Directors as
advised by outside counsel, Roberts will, through its Board of Directors,
recommend to its shareholders approval of all matters required to be so
approved.  Roberts shall use its best efforts to cause the Proxy Statement to be
mailed to Roberts' shareholders as promptly as practicable after the Form F-4 is
declared effective under the Securities Act and, if necessary, after the Proxy
Statement shall have been so mailed, promptly circulate amended, supplemental or
supplemented proxy materials and, if required in connection therewith, resolicit
proxies, it being understood that Roberts shall not be required to hold more
than one meeting of shareholders.

          8.3.  Shire Shareholders Meeting.  Shire will, as soon as
                --------------------------
practicable following the date of this Agreement, duly call, give notice of,
convene and hold an extraordinary general meeting of its ordinary shareholders
(the "Shire Shareholders Meeting") for the purpose of obtaining the Shire
      --------------------------
Shareholder Approval.  Except as required to comply with the fiduciary duties of
the Board of Directors as advised by outside counsel, Shire will, through its
Board of Directors, recommend to its shareholders approval of all such matters
required to be so approved.  In connection with the Shire Shareholders Meeting
(i) Shire will, as soon as practicable after the date of this Agreement, prepare
and file with the LSE, and will use its best efforts to have cleared by the LSE
and will thereafter mail to
<PAGE>

                                      -70-

its shareholders the UK Disclosure Documents, which will comply with all legal
requirements applicable to the Shire Shareholders Meeting and (ii) if necessary,
after the UK Disclosure Documents have been so posted, promptly circulate
amended, supplemental or supplemented materials and, if required in connection
therewith, resolicit votes, it being understood that Shire shall not be
obligated to hold more than one meeting of shareholders.

          8.4.  Acquisition Sub Actions.  Shire will take all action within
                -----------------------
its control which is necessary or appropriate to cause Acquisition Sub to
perform its obligations under this Agreement and to consummate the transactions
contemplated hereby.

                                   ARTICLE IX


                       TERMINATION, AMENDMENT AND WAIVER

          9.1.  Termination.  This Agreement may be terminated at any time
                -----------
prior to the Effective Time, whether before or after the Roberts Shareholder
Approval or the Shire Shareholder Approval:

          (a)  by mutual written consent of Shire and Roberts;

          (b)  by either Shire or Roberts upon notice thereof given in writing
     to the other party if (i) any governmental entity shall have issued an
     order, decree or ruling or taken any other action permanently enjoining,
     restraining or otherwise prohibiting the consummation of the Merger and
     such order, decree or ruling or other action shall have become final and
     nonappealable (a "Final Order") or (ii) the Effective Time has not occurred
                       -----------
     on or before December 31, 1999 unless a later date is established by mutual
     written consent of Shire and Roberts or unless the failure to consummate
     the Merger is the result of a breach of a covenant set forth in this
     Agreement or a misrepresentation or breach of any warranty set forth in
     this Agreement by the party seeking to terminate this Agreement;

          (c)  by the Board of Directors of Shire or Roberts, if (x) the Shire
     Shareholder Approval shall fail to be obtained upon a vote therefor taken
     at the Shire Shareholders Meeting or (y) Roberts Shareholder Approval shall
     fail
<PAGE>

                                      -71-

     to be obtained upon a vote therefor taken at the Roberts Shareholders
     Meeting, unless due to delay or default on the part of Roberts, in the case
     of the Roberts Shareholder Approval, or due to delay or default on the part
     of Shire or Acquisition Sub, in the case of the Shire Shareholder Approval;

          (d)  by action of the Board of Directors of Shire and notice thereof
     given in writing to Roberts if (i) there has been a breach in any material
     respect (except that where any statement in a representation or warranty
     includes a standard of materiality, such statement shall be true and
     correct in all respects giving effect to such standard) of any
     representation, warranty, covenant or agreement on the part of Roberts set
     forth in this Agreement which breach is not curable on or prior to December
     31, 1999 or (ii) the Board of Directors of Roberts (x) fails to recommend
     the approval of this Agreement and the Merger to Roberts' shareholders in
     accordance with Section 8.2 hereof, or (y) withdraws or amends or modifies
     in a manner adverse to Shire its recommendation or approval in respect of
     this Agreement or the Merger or fails to reconfirm such recommendation
     within 5 business days of a reasonable written request for such
     confirmation by Shire;

          (e)  by the Board of Directors of Shire if they shall reasonably
     determine that a proposal for a Shire Acquisition Transaction constitutes a
     Shire Superior Proposal; provided, however, that Shire may not terminate
                              --------  -------
     this Agreement pursuant to this clause (e) unless (i) 5 business days shall
     have elapsed after delivery to Roberts of a written notice of such
     determination by such Board of Directors and, during such 5-business-day
     period, Shire shall have informed Roberts of the material terms and
     conditions and financing arrangements of such proposal for a Shire
     Acquisition Transaction and the identity of the person or group making such
     proposal for a Shire Acquisition Transaction and (ii) at the end of such 5-
     business-day period, such Board of Directors shall continue reasonably to
     believe that such proposal for a Shire Acquisition Transaction constitutes
     a Shire Superior Proposal and promptly thereafter Shire shall enter into a
     definitive acquisition, merger or similar agreement to effect such Shire
     Superior Proposal;

          (f)  by action of the Board of Directors of Roberts and notice thereof
     given in writing to Shire if (i) there is a breach in any material respect
     (except that where any
<PAGE>

                                      -72-

     statement in a representation or warranty includes a standard of
     materiality, such statement shall be true and correct in all respects
     giving effect to such standard) of any representation, warranty, covenant
     or agreement on the part of Shire or Acquisition Sub set forth in this
     Agreement which breach is not curable on or prior to December 31, 1999 or
     (ii) the Board of Directors of Shire (x) fails to recommend the approval of
     this Agreement and the Merger to Shire's shareholders in accordance with
     Section 8.3 hereof, or (y) withdraws or amends or modifies in a manner
     adverse to Roberts its recommendation or approval in respect of this
     Agreement or the Merger or fails to reconfirm such recommendation within 5
     business days of a reasonable written request for such confirmation by
     Roberts; or

          (g)  by the Board of Directors of Roberts if they shall reasonably
     determine that a proposal for a Roberts Acquisition Transaction constitutes
     a Roberts Superior Proposal; provided, however, that Roberts may not
                                  --------  -------
     terminate this Agreement pursuant to this clause (g) unless (i) 5 business
     days shall have elapsed after delivery to Shire of a written notice of such
     determination by such Board of Directors and, during such 5-business-day
     period, Roberts shall have informed Shire of the material terms and
     conditions and financing arrangements of such proposal for a Roberts
     Acquisition Transaction and the identity of the person or group making such
     proposal for a Roberts Acquisition Transaction and (ii) at the end of such
     5-day-business period, such Board of Directors shall continue reasonably to
     believe that such proposal for a Roberts Acquisition Transaction
     constitutes a Roberts Superior Proposal and promptly thereafter Roberts
     shall enter into a definitive acquisition, merger or similar agreement to
     effect such Roberts Superior Proposal.

          9.2.  Effect of Termination.  In the event of termination of this
                ---------------------
Agreement as provided in Section 9.1, this Agreement shall forthwith become void
and have no effect and there shall be no liability or obligation on the part of
Shire, Roberts, Acquisition Sub or any their respective officers or directors
other than provisions of the last sentence of Section 4.4, the last sentence of
Section 5.4, Section 10.9, Section 10.10 and this Section 9.2, which will
survive termination and except to the extent that such termination results from
the willful and material breach by a party of any of its representations,
warranties, covenants or agreements set forth in this Agreement.
<PAGE>

                                      -73-

          (b)  If (x) Shire shall have terminated this Agreement pursuant to
Section 9.1(d)(ii) or (y) Roberts shall have terminated this Agreement pursuant
to Section 9.1(g), or (z) Shire or Roberts shall have terminated this Agreement
pursuant to Sections 9.1(b)(ii) or (c)(y) following the public announcement
(other than by Shire or any of its affiliates) of a proposal for a Roberts
Acquisition Transaction by any person (other than the transactions contemplated
by this Agreement) and such termination was not solely the result of any action
or inaction by Shire which resulted in the failure of the conditions in Section
7.1(a), (b) or (c) or Section 7.2, and, prior to or within six months after any
termination described in this clause (z), Roberts (or any of its Subsidiaries)
shall have entered into a definitive agreement for, or shall have consummated, a
Roberts Acquisition Transaction, in which the consideration received by Roberts
or its shareholders is equal to or greater than the value of the Merger
Consideration on the date of this Agreement then, in any of such cases, Roberts
shall pay Shire a termination fee of $30.0 million, provided, however, no fee
                                                    --------  -------
shall be payable pursuant to this Section 9.2(b) if at the time of termination
of this Agreement pursuant to Section 7.1(a) either (aa) the waiting period
under the HSR Act (including any voluntary extension or such period) shall not
have expired or (bb) any governmental entity is asserting an objection under
applicable antitrust laws to the transactions contemplated by this Agreement or
(cc) a Final Order has been issued and remains outstanding.  Any fee payable
under this Section 9.2(b) shall be paid in same day funds (A) contemporaneous
with a termination described in either clause (x) or (y) of this Section 9.2(b),
and no notice of termination pursuant to such sections shall be effective and
this Agreement shall not terminate, until such termination fee is received by
Shire, or (B) concurrently with or prior to the entering into of the definitive
agreement for, or the consummation of, such Roberts Acquisition Transaction, in
the case of a termination described in clause (z) of this Section 9.2(b).

          (c)  If (x) Roberts shall have terminated this Agreement pursuant to
Section 9.1(f)(ii) or (y) Shire shall have terminated this Agreement pursuant to
Section 9.1(e), or (z) Shire or Roberts shall have terminated this Agreement
pursuant to Sections 9.1(b)(ii) or (c)(x) following the public announcement
(other than by Roberts or any of its affiliates) of a proposal for a Shire
Acquisition Transaction by any person (other than the transactions contemplated
by this Agreement) and such termination was not solely the result of any action
or inaction by Roberts which resulted in the failure of the conditions in
Section 7.1(a), (b) or (c) or Section 7.3, and, prior to or
<PAGE>

                                      -74-

within six months after any termination described in this clause (z), Shire (or
any of its Subsidiaries) shall have entered into a definitive agreement for, or
shall have consummated, a Shire Acquisition Transaction, then, in any of such
cases, Shire shall pay Roberts a termination fee of $30.0 million, provided,
                                                                   --------
however, no fee shall be payable pursuant to this Section 9.2(c) if at the time
- -------
of termination of this Agreement pursuant to Section 7.1(a) either (aa) the
waiting period under the HSR Act (including any voluntary extension or such
period) shall not have expired or (bb) any governmental entity is asserting an
objection under applicable antitrust laws to the transactions contemplated by
this Agreement or (cc) a Final Order has been issued and remains outstanding.
Any fee payable under this Section 9.2(c) shall be paid in same day funds (A)
contemporaneous with a termination described in either clause (x) or (y) of this
Section 9.2(c), and no notice of termination pursuant to such sections shall be
effective and this Agreement shall not terminate, until such termination fee is
received by Roberts, or (B) concurrently with or prior to the entering into of
the definitive agreement for, or the consummation of, such Shire Acquisition
Transaction, in the case of a termination described in clause (z) of this
Section 9.2(c).

          9.3.  Amendment.  This Agreement may be amended by the parties
                ---------
hereto at any time before or after any required approval of matters presented in
connection with the Merger by the shareholders of Roberts or the shareholders of
Shire; provided, however, that after any such approval, there shall be made no
       --------  -------
amendment that by law requires further approval by such shareholders without the
further approval of such shareholders.  This Agreement may be amended by an
instrument in writing signed on behalf of each of the parties hereto.

          9.4.  Waiver.  At any time prior to the Closing, any party may (a)
                ------
extend the time for the performance of any of the obligations or other acts of
any other party hereto, (b) waive any inaccuracies in the representations and
warranties contained in this Agreement or in any document delivered pursuant to
this Agreement or (c) subject to the proviso of Section 9.3, waive compliance
with any of the agreements of any other party or with any conditions to its own
obligations.  Except as otherwise required by law, (x) any agreement on the part
of a party hereto to any such extension or waiver shall be valid only if set
forth in an instrument in writing signed by or on behalf of such party by a duly
authorized signatory and (y) the failure of any party to this Agreement to
assert any of its
<PAGE>

                                      -75-

rights under this Agreement or otherwise shall not constitute a waiver of those
rights.

                                   ARTICLE X


                               GENERAL PROVISIONS

          10.1.  Public Statements.  Each of Shire and Acquisition Sub, on the
                 -----------------
one hand, and Roberts, on the other hand, agree that neither they nor their
respective directors, officers, employees or agents shall disclose to any third
party (other than to their professional advisers) or publicly issue any press
release or other statement to the press or any third party with respect to this
Agreement or transactions contemplated hereby, except as may be required by law
or the rules of the American Stock Exchange or LSE rule, without the consent of
the other parties hereto.

          10.2.  Notices.  All notices and other communications hereunder
                 -------
shall be in writing (including telex or similar writing) and shall be deemed
given if delivered in person or by messenger, cable, telegram or telex or
facsimile transmission or by a reputable overnight delivery service which
provides for evidence of receipt to the parties at the following addresses or
telecopier numbers (or at such other address or telecopy number for a party as
shall be specified by like notice):

          (a)  if to Shire or Acquisition Sub, to:

               Shire Pharmaceuticals Group plc
               East Anton
               Andover, Hants  SP10 5RG
               United Kingdom
               Telecopy:  011 44 1 264 334 658
               Attention:  Rolf Stahel, Chief Executive

               with a copy to:

               John P. Mitchell, Esq.
               Cahill Gordon & Reindel
               80 Pine Street
               New York, New York  10005
               USA
               Telephone:  (212) 701-3000
               Telecopy:  (212) 269-5420
<PAGE>

                                      -76-

          (b)  if to Roberts, to:

               Roberts Pharmaceutical Corporation
               Meridian Center II
               4 Industrial Way West
               Eatontown, NJ  07724
               Telecopy:  (732) 676-1300
               Attention:  General Counsel

               with a copy to:

               Lawrence Lederman, Esq.
               Milbank, Tweed, Hadley & McCloy LLP
               One Chase Manhattan Plaza
               New York, New York  10005
               USA
               Telecopy:  (212) 530-5219

          10.3.  Interpretation.  When reference is made in this Agreement to
                 --------------
a Subsection, Section, Exhibit or Schedule, such reference is to a Subsection or
Section of or an Exhibit or Schedule to, this Agreement unless otherwise
indicated.  The table of contents and headings contained in this Agreement are
for reference purposes only and shall not affect in any way the meaning or
interpretation of this Agreement.  Whenever the words "include", "includes" and
"including" are used in this Agreement, they are deemed to be followed by the
words "without limitation".  For all purposes of this Agreement, except as
otherwise expressly provided or unless the context otherwise requires, (i) the
terms defined include the plural as well as the singular, (ii) all accounting
terms not otherwise defined herein have the meanings assigned under United
States generally accepted accounting principles, and (ii) the words "herein,"
"hereof" and "hereunder" and other words of similar import refer to this
Agreement as a whole and not to any particular Article, Section, Subsection or
other subdivision.

          10.4.  Counterparts.  This Agreement may be executed in one or more
                 ------------
counterparts, all of which shall be considered one and the same agreement and
shall become effective when one or more counterparts have been signed by each of
the parties and delivered to the other parties, it being understood that all
parties need not sign the same counterpart.

          10.5.  Entire Agreement.  This Agreement (including the Exhibits and
                 ----------------
Schedules hereto) constitute the entire agreement and supersede all prior
agreements and understandings, both written and oral, among the parties with
respect to the
<PAGE>

                                      -77-

subject matter hereof; provided that the Confidentiality Agreements referred to
in Sections 4.4 and 5.4 hereof shall survive the termination of this Agreement
in accordance with their terms.

          10.6.  Governing Law.  Except where by its terms New Jersey Law is
                 -------------
governing, this Agreement shall be governed by and construed in accordance with
the laws of the State of New York, without regard to the principles of conflicts
of law of such state.

          10.7.  Validity.  The invalidity or unenforceability of any
                 --------
provision of this Agreement shall not affect the validity or enforceability of
any other provision of this Agreement, each of which shall remain in full force
and effect.

          10.8.  Assignment.  Neither this Agreement nor any of the rights,
                 ----------
interests or obligations hereunder shall be assigned by any party hereto,
whether by operation of law or otherwise, without the express prior written
consent of each of the other parties hereto.  Subject to the preceding sentence,
this Agreement will be binding upon, inure to the benefit of and be enforceable
by the parties and their respective successors.

          10.9.  Expenses.  Except as otherwise expressly provided herein,
                 --------
each party shall bear its own expenses incurred in connection with the
transactions contemplated by this Agreement.

          10.10.  Enforcement.  The parties agree that irreparable damage
                  -----------
would occur in the event that any of the provisions of this Agreement were not
performed in accordance with their specific terms or were otherwise breached.
The parties accordingly agree that the parties will be entitled to an injunction
or injunctions to prevent breaches of this Agreement and to enforce specifically
the terms and provisions of this Agreement in any court of the United States
located in the State of New York, Borough of Manhattan, or in New York state
court located in the Borough of Manhattan, this being in addition to any other
remedy to which they are entitled at law or in equity.  In addition, each of the
parties hereto (i) consents to submit itself to the personal jurisdiction of any
Federal court located in the State of New York, Borough of Manhattan, or any New
York state court located in the Borough of Manhattan if any dispute arises out
of the Agreement or any of the transactions contemplated by this Agreement, (ii)
agrees that it will not attempt to deny or defeat such personal jurisdic-
<PAGE>

                                      -78-

tion by motion or other request for leave from any such court and (iii) agrees
that it will not bring any action relating to this Agreement in any court other
than such a Federal or state court sitting in the State of New York located in
the Borough of Manhattan.
<PAGE>

                                      -79-

          IN WITNESS WHEREOF, Shire, Acquisition Sub and Roberts have caused
this Agreement to be executed and delivered by their respective duly authorized
officers, all as of the date first above written.

                              SHIRE PHARMACEUTICALS GROUP PLC

                              By:     /s/ Rolf Stahel
                                   ------------------
                                    Name:  Rolf Stahel
                                    Title:  Chief Executive

                              RUBY ACQUISITION SUB INC.

                              By:     /s/ Rolf Stahel
                                   ------------------
                                    Name:  Rolf Stahel
                                    Title:  President

                              ROBERTS PHARMACEUTICAL CORPORATION

                              By:     /s/ John T. Spitznagel
                                   -------------------------
                                    Name:  John T. Spitznagel
                                    Title:  President

<PAGE>

Exhibit 21.1
- ------------

                             List of Subsidiaries


                                                Jurisdiction of Incorporation
Name                                                   of Organization
- ----                                            -----------------------------


Shire Holdings Limited                          Bermuda
Shire Pharmaceuticals Limited                   England and Wales
Shire Pharmaceutical Development Limited        England and Wales
Shire Pharmaceutical Contracts Ltd              England and Wales
Rybar Laboratories Limited                      England and Wales
Shire Holdings Europe Limited                   England and Wales
The Endocrine Centre Limited                    England and Wales
Sparkleflame Limited                            England and Wales
Ruby Acquisition Sub Inc.                       New Jersey
Shire Laboratories Inc.                         Delaware
Shire Richwood Inc.                             Kentucky
Shire Partners                                  Delaware
Shire Supplies U.S. LLC                         Delaware
Shire International Licensing BV                Netherlands
Laboratoires Murat SA                           France
Fuisz Pharma Beteiligungs GmbH                  Germany
Fuisz Technologies Holding GmbH                 Germany
Fuisz Pharma GmbH & Co. KG                      Germany

<PAGE>

                                                                    Exhibit 23.1



                                    ARTHUR
                                   ANDERSEN


As independent public accountants, we hereby consent to the incorporation by
reference in this registration statement of our report dated 11 March 1999
included in Shire Pharmaceutical Group plc's Form 20-F for the year ended 31
December 1998 and to all references to our Firm included in this registration
statement.

/s/ Arthur Andersen

Arthur Andersen
Chartered Accountants

Reading
UK


12 November 1999

<PAGE>

                                                                    EXHIBIT 23.2

                        CONSENT OF INDEPENDENT AUDITORS

We consent to the reference to our firm under the caption "experts" in the
Registration Statement Form F-4 for Shire Pharmaceuticals Group plc filed on or
about November 11, 1999, and to the incorporation by reference of our reports
dated March 1, 1997, with respect to the consolidated financial statements for
the years ended December 31, 1996 and 1995, of Richwood Pharmaceuticals Company,
Inc.

                                                           /s/ Ernst & Young LLP

Cincinnati, Ohio
November 11, 1999

<PAGE>

                                                                    EXHIBIT 23.3

                      CONSENT OF INDEPENDENT ACCOUNTANTS

We consent to the incorporation by reference in the registration statement on
Form F-4 of our report, dated January 30, 1997, on our audits of the financial
statements of Pharmavene, Inc. as of December 31, 1996, and for the year then
ended, and for the period February 16, 1990, (inception) to December 31, 1996,
which report is included in Shire Pharmaceuticals Group plc's Form 6-K dated
August 30, 1999. We also consent to the reference to our firm under the caption
"Experts".


                                                  /s/ PricewaterhouseCoopers LLP
                                                  PricewaterhouseCoopers LLP


McLean, Virginia
November 12, 1999

<PAGE>

                                                                    EXHIBIT 23.4

                        Consent of Independent Auditors

We consent to the reference to our firm under the caption "Experts" and to the
use of our report dated February 16, 1999, with respect to the consolidated
financial statements and schedule of Roberts Pharmaceutical Corporation
incorporated by reference in the Proxy Statement of Roberts Pharmaceutical
Corporation that is made a part of the Registration Statement (Form F-4 No.
333-00000) and related Prospectus of Shire Pharmaceuticals Group plc dated
November 11, 1999.

                                                           /s/ Ernst & Young LLP

MetroPark, New Jersey
November 11, 1999

<PAGE>

                                                                    EXHIBIT 23.5


                      CONSENT OF INDEPENDENT ACCOUNTANTS

We hereby consent to the incorporation by reference in this Registration
Statement on Form F-4 of Shire Pharmaceuticals PLC of our report dated February
5, 1998 relating to the financial statements and financial statement schedules
appearing in Roberts Pharmaceutical Corporation Annual Report on Form 10-K for
the years ended December 31, 1997 and 1996.  We also consent to the references
to us under the headings "Experts" and "Selected Financial Data" in such
Registration Statement.


/s/ PricewaterhouseCoopers LLP

Florham Park, New Jersey
November 12, 1999

<PAGE>
                                                                    Exhibit 99.3

                        CONSENT OF NOMINEE FOR DIRECTOR


Shire Pharmaceuticals Group plc
East Anton Andover
Hampshire SP10 5RG
United Kingdom

ATTN:        Dr. James Cavanaugh
             Chairman of the Board of Directors


        I hereby consent to be named in a Registration Statement on Form F-4
(including the Prospectus-Proxy Statement) as a nominee for director of Shire
Pharmaceuticals Group plc (the "Company") and to all references to me in the
Prospectus-Proxy Statement. This consent is being given with respect to the
Company's Registration Statement on Form F-4 to be filed with the Securities and
Exchange Commission and any amendments filed thereto regarding the registration
of ordinary shares of the Company to be issued in connection with the merger
with Roberts Pharmaceutical Corporation.

        Signed this 11th day of November, 1999.



                                        /S/ Ronald M. Nordmann
                                            ------------------
                                            Ronald M. Nordmann

<PAGE>

                                                                    Exhibit 99.4



                        CONSENT OF NOMINEE FOR DIRECTOR


Shire Pharmaceuticals Group plc
East Anton Andover
Hampshire SP10 5RG
United Kingdom


ATTN:  Dr. James Cavanaugh
       Chairman of the Board of Directors


        I hereby consent to be named in a Registration Statement on Form F-4
(including the Prospectus-Proxy Statement) as a nominee for director of Shire
Pharmaceuticals Group plc (the "Company") and to all references to me in the
Prospectus-Proxy Statement. This consent is being given with respect to the
Company's Registration Statement on Form F-4 to be filed with the Securities and
Exchange Commission and any amendments filed thereto regarding the registration
of ordinary shares of the Company to be issued in connection with the merger
with Roberts Pharmaceutical Corporation.

        Signed this 11th day of November, 1999.


                                        /s/ Joseph E. Smith
                                        -------------------
                                        Joseph E. Smith

<PAGE>

                                                                    Exhibit 99.5


                        CONSENT OF NOMINEE FOR DIRECTOR


Shire Pharmaceuticals Group plc
East Anton Andover
Hampshire SP10 5RG
United Kingdom


ATTN:  Dr. James Cavanaugh
       Chairman of the Board of Directors


        I hereby consent to be named in a Registration Statement on Form F-4
(including the Prospectus-Proxy Statement) as a nominee for director of Shire
Pharmaceuticals Group plc (the "Company") and to all references to me in the
Prospectus-Proxy Statement. This consent is being given with respect to the
Company's Registration Statement on Form F-4 to be filed with the Securities and
Exchange Commission and any amendments filed thereto regarding the registration
of ordinary shares of the Company to be issued in connection with the merger
with Roberts Pharmaceutical Corporation.

        Signed this 11th day of November, 1999.


                                        /s/ Zola P. Horovitz
                                        ---------------------------
                                        Zola P. Horovitz, Ph.D.


<PAGE>


                                                                    Exhibit 99.6


                        CONSENT OF NOMINEE FOR DIRECTOR


Shire Pharmaceuticals Group plc
East Anton Andover
Hampshire SP10 5RG
United Kingdom


ATTN:  Dr. James Cavanaugh
       Chairman of the Board of Directors


        I hereby consent to be named in a Registration Statement on Form F-4
(including the Prospectus-Proxy Statement) as a nominee for director of Shire
Pharmaceuticals Group plc (the "Company") and to all references to me in the
Prospectus-Proxy Statement. This consent is being given with respect to the
Company's Registration Statement on Form F-4 to be filed with the Securities and
Exchange Commission and any amendments filed thereto regarding the registration
of ordinary shares of the Company to be issued in connection with the merger
with Roberts Pharmaceutical Corporation.

        Signed this 11th day of November, 1999.


                                        /s/ John T. Spitznagel
                                        ---------------------------
                                        John T. Spitznagel



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