SHIRE PHARMACEUTICALS GROUP PLC
424B2, 1999-11-23
PHARMACEUTICAL PREPARATIONS
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<PAGE>
                                                     RULE NO. 424(b)(2)
                                                     REGISTRATION NO. 333-90947



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

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

                   NOTICE OF SPECIAL MEETING OF SHAREHOLDERS
                        TO BE HELD ON DECEMBER 22, 1999

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

To the Shareholders of
Roberts Pharmaceutical Corporation:

   A special meeting of shareholders of Roberts Pharmaceutical Corporation will
be held on December 22, 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
November 23, 1999
<PAGE>

      Shire Pharmaceuticals Group plc  Roberts Pharmaceutical Corporation

   Roberts Pharmaceutical Corporation is sending this Prospectus-Proxy
Statement to its shareholders in connection with a solicitation of proxies by
the board of directors of Roberts, 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 consider and vote on a proposal to approve and
adopt the merger agreement. If the Roberts shareholders approve the merger,
each share of Roberts common stock will represent a 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 November 22, 1999, such per share prices were $32.25, 657p
and $31.50, respectively.

   Roberts board of directors urges Roberts shareholders to read and carefully
consider the information 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 November 22, 1999 and it is
first being mailed to shareholders on or about this date.
<PAGE>

                               TABLE OF CONTENTS

<TABLE>
<CAPTION>
                                                                           Page
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<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.....................................   10
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
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<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 ..................................... A-1
Annex B--Opinion of PaineWebber Incorporated .............................. B-1
Annex C--Opinion of Bear, Stearns & Co. Inc. .............................. C-1
</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 December 10, 1999.

   Roberts has filed the following documents with the SEC (File No. 1-10432)
which are incorporated in this document by reference: (a) Roberts' Annual
Report on Form 10-K and Form 10-K/A 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 and Form 10-Q/A for the
quarterly period ended June 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.

   Shire has filed the following documents with the SEC (File No. 0-29630)
which are incorporated in this document by reference: (a) Shire's Annual Report
on Form 20-F/A 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.

   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 December 23, 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
   which allows 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. Shire
  will give you 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 Roberts can count the vote of your shares 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 which we have enclosed with this
   Prospectus-Proxy Statement and returning it no later than December 10,
   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 the Company Secretary, Roberts Pharmaceutical Corporation, Meridian
   Center II, 4 Industrial Way West, Eatontown, New Jersey 07724 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 broker will not vote your shares
   for or against the merger.

Q. Should I send in my stock certificates now?

A. No. After Shire and Roberts complete the merger, 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 we
   can count the vote of your Roberts shares 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 in this Prospectus-Proxy
Statement. This summary 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 should 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. Shire and Roberts will
determine the exchange ratio based on the average trading price of the ADSs for
the fifteen consecutive trading days ending three trading days before the date
they consummate the merger.

                                 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), for the
treatment of Alzheimer's disease for which Shire recently completed Phase III
clinical trials.

   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, using 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 exist if at least a majority of the
Roberts shares are present or represented by proxy. If there is a quorum, 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 holders of
approximately 21.3% of the outstanding shares of common stock of Roberts have
already 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 you will receive in exchange for each share of Roberts common
stock, ADSs, each representing three ordinary shares, unless you choose to
receive Shire ordinary shares. 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 November 22,
1999, the most recent practicable date prior to filing of this document, the
average trading price of the ADSs is $31.98. Based upon this average, you would
receive approximately 1.0427ADSs (or 3.1280 ordinary shares) in the merger for
each Roberts share you own. However, the actual number of ADSs (or ordinary
shares) which Shire will issue 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. Shire will not issue fractional ADSs or ordinary shares.
Instead, Shire will pay you cash for any fractional ADS or ordinary share which
you are otherwise entitled to receive 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 parties expect
the principal benefits of the merger 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 Shire offered 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.

  .  Shire's board will appoint some of Roberts' directors as 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 parties intend the merger to qualify as a "pooling of interests"
transaction under U.S. generally accepted accounting principles, which

                                       8
<PAGE>

means that the companies will be treated as if they had always 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 read carefully the discussion in "Material Tax Consequences" and
other sections of this Prospectus-Proxy Statement. We suggest you 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 they satisfy or waive
a number of conditions. 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 shareholders of Roberts and Shire approve and adopt the merger
agreement and the other conditions to the merger are satisfied or, where
permissible, waived, Shire and Roberts will consummate the merger by filing 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. If Shire exercises the option, 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.

   The parties made no submission 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. The SEC
has not required full U.S. GAAP financial statements of Shire which is a
"foreign private issuer." 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 Shire anticipates 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, the SEC will require publication of full U.S.
GAAP financial statements 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,
which requires such accounts to be filed on an annual basis, within seven
months of the accounting period end. Such U.K. GAAP accounts 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:
                                       11
<PAGE>


 i. Accounting for business combinations

  (a) Goodwill

   Prior to December 31, 1998, goodwill arising from the acquisition of a
business could be written 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>
                                                      Year Ended
                         15 Months                     June 30,
                           Ended      ---------------------------------------------
                         June 30,
                          1994(1)         1995            1996            1997
                       -------------  -------------  --------------  --------------
<S>                    <C>            <C>            <C>             <C>
Statement of
 Operations
 Data:
U.K. GAAP
Turnover/(revenues)..  (Pounds)7,465  (Pounds)6,102  (Pounds)21,043  (Pounds)23,072
Operating
 profit/(loss)..              (2,349)        (6,127)          2,569          (1,399)
Profit/(loss) on
 ordinary
 activities
 before
 taxation.......              (2,244)        (7,197)          2,722            (146)
Profit/(loss) on
 ordinary
 activities
 after
 taxation.......              (2,190)        (7,200)          2,555            (146)
Fully diluted
 earnings/(loss)
 per ordinary
 share..........              (0.119)        (0.394)          0.057          (0.002)
Weighted average
 ordinary shares
 outstanding....              18,288         18,289          45,208          67,153
U.S. GAAP
Revenues........                                             21,043          23,072
Income/(loss)
 from operations
 before write-
 off of in-
 process
 research and
 development....                                              2,302          (1,659)
(Loss)/income
 from
 operations.....                                            (12,426)        (52,285)
(Loss)/income
 before income
 taxes..........                                            (12,273)        (51,032)
Net
 (loss)/income..                                            (12,189)        (50,238)
Fully diluted
 net
 (loss)/income
 per ordinary
 share(4).......                                              (0.28)          (0.75)
Fully diluted
 net
 (loss)/income
 per ADS........                                              (0.83)          (2.24)
<CAPTION>
                                                       Year Ended                      Nine Months Ended
                         Six Months                   December 31,                       September 30,
                            Ended       -------------------------------------------    -----------------
                        December 31,                                                    Actual
                            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>
Statement of
 Operations
 Data:
U.K. GAAP
Turnover/(revenues)..  (Pounds) 28,605  (Pounds)41,798  (Pounds)80,328   $131,738   (Pounds)92,516 $151,726
Operating
 profit/(loss)..                 2,230           1,582           7,879     12,922           21,501   35,262
Profit/(loss) on
 ordinary
 activities
 before
 taxation.......                 2,452           2,411           9,099     14,922           23,153   37,971
Profit/(loss) on
 ordinary
 activities
 after
 taxation.......                  (380)           (421)          6,247     10,245           17,363   28,475
Fully diluted
 earnings/(loss)
 per ordinary
 share..........                (0.003)         (0.004)          0.043      0.071            0.117    0.192
Weighted average
 ordinary shares
 outstanding....               112,660          93,145         144,399    144,399          148,526  148,526
U.S. GAAP
Revenues........                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....                (1,469)         (2,289)         (2,143)    (3,514)          10,018   16,430
(Loss)/income
 from
 operations.....                (1,469)        (52,915)         (2,143)    (3,514)          10,018   16,430
(Loss)/income
 before income
 taxes..........                (1,247)        (52,086)           (923)    (1,514)          11,670   19,139
Net
 (loss)/income..                (2,857)        (53,606)          2,179      3,574            5,634    9,240
Fully diluted
 net
 (loss)/income
 per ordinary
 share(4).......                 (0.03)          (0.57)           0.02       0.03             0.04     0.06
Fully diluted
 net
 (loss)/income
 per ADS........                 (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. You should read the data presented below
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. You should read the pro forma combined financial data
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>
                                          Shire                                     Roberts
                   ------------------------------------------------------  --------------------------
                                   Adjustments                    U.S.       U.S.
                     U.K. GAAP         (1)        U.S. GAAP      GAAP(2)    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)80,328  (Pounds)--   (Pounds)80,328  $ 133,344  $ 175,445  (Pounds)105,690
Operating
 expenses........         (72,449)     (10,022)        (82,471)  (136,902)  (148,067)         (89,197)
Operating
 income/(loss)...           7,879      (10,022)         (2,143)    (3,558)    27,378           16,493
Interest income..           1,434          --            1,434      2,380      4,108            2,475
Interest
 expense.........            (214)         --             (214)      (355)    (6,157)          (3,709)
Other, net.......             --           --              --         --        (318)            (192)
Income/(loss)
 before income
 taxes...........           9,099      (10,022)           (923)    (1,533)    25,011           15,067
Income taxes.....          (2,852)       5,954           3,102      5,149     (8,224)          (4,954)
Net
 income/(loss)...           6,247       (4,068)          2,179      3,616     16,787           10,113
Earnings/(loss)
 per ordinary
 share
 -- basic........            0.05          --             0.02       0.03       0.54             0.33
 -- diluted......            0.04          --             0.02       0.03       0.53             0.32
Weighted average
 ordinary shares
 outstanding
 -- basic........         136,924          --          136,924    136,924     31,049           31,049
 -- diluted......         144,399          --          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........
 -- 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 Pro Forma
                   ----------------------------
                                       U.S.
                    U.S. GAAP(5)     GAAP(6)
                   ---------------- -----------
<S>                <C>              <C>
Total revenue....  (Pounds)186,018  $  308,789
Operating
 expenses........         (171,668)  (284 ,969)
Operating
 income/(loss)...           14,350      23,820
Interest income..            3,909       6,488
Interest
 expense.........           (3,923)     (6,512)
Other, net.......             (192)       (318)
Income/(loss)
 before income
 taxes...........           14,144      23,478
Income taxes.....           (1,852)     (3,075)
Net
 income/(loss)...           12,292      20,403
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........             0.05        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 statement does not reflect costs
    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.
    The costs attributable to professional fees, UK stamp duty tax levied on
    the value of the Shire ordinary shares issued under the merger agreement
    and the distribution of proxy materials are estimated at $35 million. Shire
    intends to take a restructuring charge in the fourth quarter of 1999
    following consummation of the merger. The exact amount of the restructuring
    charge has not yet been determined, but will be accounted for under the
    requirements of EITF 94-3 when determined.

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
4th Quarter (through
 November 22, 1999) .... $33.19    $27.44 (Pounds)6.87 (Pounds)5.59 $34.00 $29.88
3rd Quarter ............  29.31     23.75         6.13         5.01  30.25  21.69
2nd Quarter.............  26.00     18.88         5.28         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 November 22, 1999, such per share prices were
$31.50, $32.25 and 657p, 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, we can not
determine today the value you will receive for your Roberts shares. 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
restrict our ability to sell one or more of our products or sell them at a
profit. 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. 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, we could become insolvent. 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.

   We may not achieve sustained profitability due to 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
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 our
     pharmaceutical products;

  .  spending on research and development of our products;

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

  .  cost increases from our third-party manufacturers;

  .  supply interruptions;

  .  the expiration of our intellectual property protection;

  .  the mix of products sold by us;

                                       35
<PAGE>

  .  changes in our marketing and sales expenditures; and

  .  market acceptance of 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 we fail to adequately protect 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 products

                                       36
<PAGE>

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 which decrease
sales or reduce 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 if we are found liable in some or all of those lawsuits for
damages in excess of our assets we would be required to reorganize or seek
bankruptcy protection. 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 98 of these suits, the plaintiffs have specifically alleged
in the complaint or subsequent discovery 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 November 22, 1999, the noon buying rate was $1.62 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
<PAGE>

                              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 December 22,
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 19, 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 .50% and
1.50% over the higher of DLJ's prime rate or the Federal Funds Rate plus 1/2 of
1% or between 1.50% and 2.50% over the London Interbank Overnight rate, in each
case depending on the credit rating of the indebtedness incurred under the new
credit facility. 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 (in
the case of licenses, subject to the consent of the other parties thereto)
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

         .......................        21.50         1.2558        27.00
                                        22.00         1.2273        27.00
   Fixed Price                          22.50         1.2000        27.00
                                        23.00         1.1739        27.00
         .......................        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

         .......................        29.50         1.1186        33.00
                                        30.00         1.1000        33.00
   Fixed Price                          30.50         1.0820        33.00
                                        31.00         1.0645        33.00
         .......................        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

                                       73
<PAGE>

   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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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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                           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 for 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. Roberts has received the opinion of Milbank, Tweed,
Hadley & McCloy LLP 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. This opinion fulfills
one of the conditions to the merger agreement. See "The Merger Agreement--
Conditions to Consummation of the Merger." This tax opinion is 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.

   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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<PAGE>

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 is 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
143,722,798 ordinary shares of 5p each are in issue at the date of this
Prospectus-Proxy Statement. A maximum of 278,511,666 ordinary shares of 5p each
will be in issue 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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   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.

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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%

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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>

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


                          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

<TABLE>
<CAPTION>
                                                                            Page
                                                                            ----
                                     ARTICLE I

                                    DEFINITIONS

 <C>    <S>                                                                 <C>
  1.1.  Definitions.......................................................   A-1
<CAPTION>
                                    ARTICLE II

                   THE MERGER; CONVERSION AND EXCHANGE OF STOCK

 <C>    <S>                                                                 <C>
  2.1.  Merger............................................................   A-6
  2.2.  Effective Time....................................................   A-6
  2.3.  Effects of the Merger.............................................   A-6
  2.4.  Further Assurances................................................   A-6
  2.5.  Merger Consideration..............................................   A-7
  2.6.  Exchange Provisions...............................................   A-8
  2.7.  Consideration for Ordinary Shares.................................   A-9
  2.8.  Tax-Free Reorganization...........................................   A-9
<CAPTION>
                                    ARTICLE III

                          REPRESENTATIONS AND WARRANTIES

 <C>    <S>                                                                 <C>
  3.1.  Representations and Warranties of Roberts.........................   A-9
        (a)Organization; Standing and Power...............................   A-9
        (b)Subsidiaries and Investments...................................   A-9
        (c)Capitalization.................................................   A-9
        (d)Authority......................................................  A-10
        (e)Noncontravention...............................................  A-10
        (f)Government Approval; Consents..................................  A-10
        (g)SEC Documents..................................................  A-11
        (h)Information Supplied...........................................  A-11
        (i)Absence of Certain Changes or Events...........................  A-11
        (j)Compliance with Law............................................  A-12
        (k)Affiliate Arrangements.........................................  A-12
        (l)Transaction Fees...............................................  A-12
        (m)Litigation.....................................................  A-12
        (n)Taxes and Tax Returns..........................................  A-12
        (o)Real Property..................................................  A-13
        (p)Licenses, Permits and Authorizations...........................  A-13
        (q)ERISA and Employee Matters.....................................  A-14
        (r)Labor Relations................................................  A-14
        (s)Intellectual Property Rights...................................  A-15
        (t)Insurance......................................................  A-15
        (u)Books and Records..............................................  A-15
        (v)Undisclosed Liabilities........................................  A-16
        (w)FDA, DEA Matters...............................................  A-16
        (x)Environmental Matters..........................................  A-17
        (y)Products.......................................................  A-18
        (z)Marketing Practices............................................  A-18
        (aa)Affiliates....................................................  A-18
        (bb)Pooling.......................................................  A-19
        (cc)Business Combination..........................................  A-19
</TABLE>

                                      A-i
<PAGE>

<TABLE>
<CAPTION>
                                                                            Page
                                                                            ----
 <C>    <S>                                                                 <C>
  3.2.  Representations and Warranties of Shire...........................  A-19
        (a)Organization; Standing and Power...............................  A-19
        (b)Subsidiaries and Investments...................................  A-19
        (c)Capitalization.................................................  A-19
        (d)Authority......................................................  A-20
        (e)Noncontravention...............................................  A-20
        (f)Government Approval; Consents..................................  A-20
        (g)Reports and Financial Statements...............................  A-20
        (h)Information Supplied...........................................  A-21
        (i)Absence of Certain Changes or Events...........................  A-21
        (j)Compliance with Law............................................  A-22
        (k)Affiliate Arrangements.........................................  A-22
        (l)Transaction Fees...............................................  A-22
        (m)Litigation.....................................................  A-22
        (n)Taxes and Tax Returns..........................................  A-22
        (o)Real Property..................................................  A-22
        (p)Licenses, Permits and Authorizations...........................  A-23
        (q)ERISA and Employee Matters.....................................  A-23
        (r)Labor Relations................................................  A-24
        (s)Intellectual Property Rights...................................  A-24
        (t)Insurance......................................................  A-25
        (u)Books and Records..............................................  A-25
        (v)Undisclosed Liabilities........................................  A-25
        (w)FDA, DEA Matters...............................................  A-25
        (x)Environmental Matters..........................................  A-26
        (y)Products.......................................................  A-27
        (z)Marketing Practices............................................  A-28
        (aa)Ordinary Shares...............................................  A-28
        (bb)Pooling.......................................................  A-28
        (cc)Merger Consideration..........................................  A-28
        (dd)Active Trade or Business......................................  A-28
        (ee)Asset Acquisitions............................................  A-28
        (ff) Ownership of Roberts Shares..................................  A-28
<CAPTION>
                                    ARTICLE IV

                               COVENANTS OF ROBERTS

 <C>    <S>                                                                 <C>
  4.1.  Regular Course of Business........................................  A-29
  4.2.  Certain Prohibited Activities.....................................  A-29
  4.3.  Notice of Certain Events..........................................  A-30
  4.4.  Access............................................................  A-30
  4.5.  Approvals.........................................................  A-30
  4.6.  No Solicitation...................................................  A-30
  4.7.  Pooling of Interests..............................................  A-31
  4.8.  ISRA..............................................................  A-31
</TABLE>


                                      A-ii
<PAGE>

<TABLE>
<CAPTION>
                                                                          Page
                                                                          ----
                                    ARTICLE V

                     COVENANTS OF SHIRE AND ACQUISITION SUB

 <C>    <S>                                                               <C>
  5.1.  Regular Course of Business......................................  A-31
  5.2.  Certain Prohibited Activities...................................  A-31
  5.3.  Notice of Certain Events........................................  A-32
  5.4.  Access..........................................................  A-32
  5.5.  Approvals.......................................................  A-32
  5.6.  No Solicitation.................................................  A-32
  5.7.  Pooling of Interests............................................  A-33
  5.8.  Indemnification.................................................  A-33
<CAPTION>
                                   ARTICLE VI

                 AGREEMENTS REGARDING OPTIONS AND OTHER BENEFITS

 <C>    <S>                                                               <C>
  6.1.  Stock Option Plans..............................................  A-34
  6.2.  Continuation of Benefits........................................  A-34
  6.3.  Severance Policy and Other Agreements...........................  A-34
  6.4.  1999 Bonus......................................................  A-34
  6.5.  Waiver of Preexisting Conditions; Credit for Deductibles;
        Service Credit..................................................  A-35
<CAPTION>
                                   ARTICLE VII

                              CONDITIONS PRECEDENT

 <C>    <S>                                                               <C>
  7.1.  Conditions to the Obligations of Each Party to Effect the
        Merger..........................................................  A-35
        (a)Shareholder Approvals........................................  A-35
        (b)Certain Approvals............................................  A-35
        (c)No Proceeding or Litigation..................................  A-35
        (d)Securities Laws..............................................  A-35
  7.2.  Additional Conditions to the Obligations of Roberts.............  A-35
        (a)Agreements...................................................  A-35
        (b)Representations and Warranties...............................  A-35
        (c)Officer's Certificate........................................  A-36
        (d)Consents from Third Parties..................................  A-36
        (e)Listing......................................................  A-36
        (f)Tax Opinions.................................................  A-36
        (g)Pooling Letter...............................................  A-36
        (h)Nasdaq.......................................................  A-36
  7.3.  Additional Conditions to the Obligations of Shire and
        Acquisition Sub.................................................  A-36
        (a)Agreements...................................................  A-36
        (b)Representations and Warranties...............................  A-36
        (c)Roberts Officer's Certificate................................  A-36
        (d)Pooling Letter...............................................  A-37
</TABLE>


                                     A-iii
<PAGE>

<TABLE>
<CAPTION>
                                                                          Page
                                                                          ----
                                  ARTICLE VIII

                                OTHER AGREEMENTS

 <C>    <S>                                                               <C>
  8.1.  Preparation of Form F-4, Form F-6, the Proxy Statement and the
        UK Disclosure Document..........................................  A-37
  8.2.  Roberts Shareholders Meeting....................................  A-37
  8.3.  Shire Shareholders Meeting......................................  A-37
  8.4.  Acquisition Sub Actions.........................................  A-37
<CAPTION>
                                   ARTICLE IX

                        TERMINATION, AMENDMENT AND WAIVER

 <C>    <S>                                                               <C>
  9.1.  Termination.....................................................  A-38
  9.2.  Effect of Termination...........................................  A-39
  9.3.  Amendment.......................................................  A-40
  9.4.  Waiver..........................................................  A-40
<CAPTION>
                                    ARTICLE X

                               GENERAL PROVISIONS

 <C>    <S>                                                               <C>
 10.1.  Public Statements...............................................  A-40
 10.2.  Notices.........................................................  A-40
 10.3.  Interpretation..................................................  A-41
 10.4.  Counterparts....................................................  A-41
 10.5.  Entire Agreement................................................  A-41
 10.6.  Governing Law...................................................  A-41
 10.7.  Validity........................................................  A-41
 10.8.  Assignment......................................................  A-42
 10.9.  Expenses........................................................  A-42
 10.10. Enforcement.....................................................  A-42
</TABLE>

<TABLE>
 <C>         <S>
 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
</TABLE>

                                      A-iv
<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.

   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.

                                      A-1
<PAGE>

     "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.

     "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).

     "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.

                                      A-2
<PAGE>

     "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.

     "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 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.

                                      A-3
<PAGE>

     "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
  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.

                                      A-4
<PAGE>

     "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).

     "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).


                                      A-5
<PAGE>

     "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 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 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,

                                      A-6
<PAGE>

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 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 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

                                      A-7
<PAGE>

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
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 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

                                      A-8
<PAGE>

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 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.

     (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

                                      A-9
<PAGE>

  (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.

     (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.

     (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

                                      A-10
<PAGE>

  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 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 interest made with respect to
  a

                                      A-11
<PAGE>

  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, 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

                                      A-12
<PAGE>

  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 "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 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.

                                      A-13
<PAGE>

     (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, 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 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

                                      A-14
<PAGE>

  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.

     (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 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

                                      A-15
<PAGE>

  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.

     (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 products, 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

                                      A-16
<PAGE>

  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 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,
  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.


                                      A-17
<PAGE>

     (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.

     (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 (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.


                                      A-18
<PAGE>

     (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 "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 jurisdictions,
  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

                                      A-19
<PAGE>

  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 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 Acquisition 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

                                      A-20
<PAGE>

  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 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 payment 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

                                      A-21
<PAGE>

  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 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 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

                                      A-22
<PAGE>

  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 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 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

                                      A-23
<PAGE>

  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, 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 knowledge 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.

                                      A-24
<PAGE>

     (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 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 or any state or
  non-U.S. regulatory agency pending or, to the best knowledge of Shire,
  threatened against or relating to Shire, any

                                      A-25
<PAGE>

  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. 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 required under applicable Environmental
  Laws to conduct its business as currently conducted and

                                      A-26
<PAGE>

  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, 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

                                      A-27
<PAGE>

  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 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 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

                                      A-28
<PAGE>

  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.

                                   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 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

                                      A-29
<PAGE>

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 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 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

                                      A-30
<PAGE>

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.

   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
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 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

                                      A-31
<PAGE>

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 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 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
Transaction, 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.


                                      A-32
<PAGE>

   (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 "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.

                                      A-33
<PAGE>

                                   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 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

                                      A-34
<PAGE>

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 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
  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

                                      A-35
<PAGE>

  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 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 satisfaction 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.

                                      A-36
<PAGE>

     (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 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 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.


                                      A-37
<PAGE>

                                   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 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 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

                                      A-38
<PAGE>

  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.

   (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 within six months
after any termination described in this clause (z), Shire (or any of its

                                      A-39
<PAGE>

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 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


                                      A-40
<PAGE>

       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

      (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
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.

                                      A-41
<PAGE>

   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
jurisdiction 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.

   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

                                                      /s/ Rolf Stahel
                                          By___________________________________
                                          Name: Rolf Stahel
                                          Title: Chief Executive

                                          RUBY ACQUISITION SUB INC.

                                                      /s/ Rolf Stahel
                                          By___________________________________
                                          Name: Rolf Stahel
                                          Title: President

                                          RUBY ACQUISITION SUB INC.

                                                      /s/ Rolf Stahel
                                          By___________________________________
                                          Name: Rolf Stahel
                                          Title: President

                                          ROBERTS PHARMACEUTICAL CORPORATION

                                                  /s/ John T. Spitznagel
                                          By___________________________________
                                          Name: John T. Spitznagel
                                          Title: President

                                      A-42
<PAGE>

Investment Banking Division

PaineWebber Incorporated
1285 Avenue of the Americas
New York, NY 10019
212 713-2000




                                                            PaineWebber

                                                            July 22, 1999

Confidential
- ------------

Board of Directors
Roberts Pharmaceutical Corporation
Meridian Center II
4 Industrial Way West
Eatontown, New Jersey 07724

Ladies and Gentlemen:

     Roberts Pharmaceutical Corporation (the "Company") and Shire
Pharmaceuticals Group plc (the "Acquiring Company") propose to enter into an
agreement (the "Agreement") pursuant to which the Company will be merged with a
wholly-owned subsidiary of the Acquiring Company in a transaction (the
"Merger") in which each share of the Company's common stock, par value $0.01 per
share (the "Shares"), will be converted into the right to receive 1.1374 (the
"Exchange Ratio") American Depositary Receipts of the Acquiring Company (the
"ADRs") or, at the option of the holder, Ordinary Shares, nominal value 5 pence
per share, of the Acquiring Company (the "Merger Consideration"). One ADR is
equal to three Ordinary Shares of the Acquiring Company. The Exchange Ratio is
subject to adjustment between 1.0427 and 1.2802 in the event of certain changes
in the price of the ADRs as set forth in the draft Agreement dated July 21,
1999. In connection with the Merger, the parties also propose to enter into an
agreement (the "Option Agreement") pursuant to which the Company will grant the
Acquiring Company an option to acquire 6,345,926 Shares which, if issued, would
represent approximately 19.9% of the total number of currently outstanding
Shares. In addition, certain shareholders of the Company holding in the
aggregate approximately 25% of the Shares propose to enter into agreements with
the Acquiring Company (the "Shareholder Agreements") pursuant to which such
shareholders will agree to vote for the approval of the Merger.

     You have asked us whether or not, in our opinion, the proposed Merger
Consideration to be received by the shareholders of the Company pursuant to the
Merger is fair to such shareholders from a financial point of view.



<PAGE>

PaineWebber



In arriving at the opinion set forth below, we have, among other things:

(1)  Reviewed the Company's Annual Reports, Forms 10-K and related financial
     information for the three fiscal years ended December 31, 1998; the
     Company's Form 10-Q and the related unaudited financial information for the
     three months ended March 31, 1999; and certain unaudited financial
     information of the Company for the six months ended June 30, 1999;

(2)  Reviewed the Acquiring Company's Annual Reports, Forms 20-F and related
     financial information for the two fiscal years ended December 31, 1998,
     and certain unaudited financial information of the Acquiring Company for
     the three months ended March 31, 1999;

(3)  Reviewed certain information, including financial forecasts, relating to
     the business, earnings, cash flow, assets and prospects of the Company and
     the Acquiring Company, furnished to us by the Company or which were
     otherwise publicly available;

(4)  Conducted discussions with members of senior management of the Company and
     the Acquiring Company concerning their respective businesses and prospects;

(5)  Reviewed the historical market prices and trading activity for the Shares
     and the ADRs and compared them with that of certain publicly traded
     companies which we deemed to be relevant;

(6)  Compared the financial position and results of operations of the Company
     and the Acquiring Company with that of certain companies which we deemed to
     be relevant;

(7)  Compared the proposed financial terms of the transactions contemplated by
     the Agreement with the financial terms of certain other mergers and
     acquisitions which we deemed to be relevant;

(8)  Reviewed a draft of the Agreement dated July 21, 1999;

(9)  Reviewed a draft of the Option Agreement dated July 21, 1999;

(10) Reviewed drafts of the Shareholder Agreements dated July 21, 1999; and,

(11) Reviewed such other financial studies and analyses and performed such other
     investigations and took into account such other matters as we deemed
     necessary, including our assessment of general economic, market and
     monetary conditions.

<PAGE>

PaineWebber


        In preparing our opinion, we have relied on the accuracy and
completeness of all information publicly available, supplied or otherwise
communicated to us by the Company and the Acquiring Company, and we have not
assumed any responsibility to independently verify such information. With
respect to the financial forecasts examined by us, we have assumed that they
were reasonably prepared on bases reflecting the best currently available
estimates and good faith judgment of the management of the Company as to the
future performance of the Company. We have also relied upon assurances of the
management of the Company and the Acquiring Company, respectively, that they are
unaware of any facts that would make the information or financial forecasts
provided to us incomplete or misleading. We have not been engaged to make, and
have not made, any independent evaluation or appraisal of the assets or
liabilities (contingent or otherwise) of the Company or the Acquiring Company
nor have we been furnished with any such evaluations or appraisals. We have also
assumed with your consent, that (i) the Merger will be accounted for under the
pooling-of-interests method of accounting under U.S. generally accepted
accounting principles, (ii) the Merger will be a tax free reorganization and
(iii) any material liabilities (contingent or otherwise, known or unknown) of
the Company and the Acquiring Company are as set forth in the consolidated
financial statements of the Company and the Acquiring Company, respectively.

        This opinion is directed to the Board of Directors of the Company and
does not constitute a recommendation to any shareholder of the Company as to how
any such shareholder should vote on the Merger. This opinion does not address
the relative merits of the Merger and any other transactions or business
strategies discussed by the Board of Directors of the Company as alternatives to
the Merger or the decision of the Board of Directors of the Company to proceed
with the Merger. We were not requested to, and did not, solicit third party
indications of interest in acquiring all or any portion of the Company.

        No opinion is expressed herein as to the price at which the securities
to be issued in the Merger to the shareholders of the Company may trade at any
time. Our opinion is based on economic, monetary and market conditions existing
on the date hereof.

        In the ordinary course of business, PaineWebber Incorporated may trade
in the securities of the Company and the Acquiring Company for our own account
and for the accounts of our customers and, accordingly, may at any time hold
long or short positions in such securities.

        PaineWebber Incorporated is currently acting as financial advisor to the
Company in connection with the Merger and will be receiving a fee in connection
with the rendering of this opinion and upon consummation of the Merger.
<PAGE>

PaineWebber



        On the basis of, and subject to the foregoing, we are of the opinion
that the proposed Merger Consideration to be received by the shareholders of the
Company pursuant to the Merger, taken as a whole, is fair to such shareholders
from a financial point of view.

        This opinion has been prepared for the information of the Board of
Directors of the Company in connection with the Merger and shall not be
reproduced, summarized, described or referred to, provided to any person or
otherwise made public or used for any other purpose without the prior written
consent of PaineWebber Incorporated, provided, however, that this letter may be
                                     --------  -------
reproduced in full in the Proxy Statement related to the Merger.



                                        Very truly yours,

                                        PAINEWEBBER INCORPORATED


                                        /s/ PaineWebber Incorporated
                                        ----------------------------

<PAGE>

                    [LETTERHEAD OF BEAR, STEARNS & CO. INC.]

July 23, 1999

Shire Pharmaceuticals Group plc
East Anton Andover
Hampshire
SP10 5RG
United Kingdom

           Attention: Board of Directors

Gentlemen:

We understand that Shire Pharmaceuticals Group plc ("Shire") and Roberts
Pharmaceutical Corporation ("Roberts") are considering a transaction pursuant
to which a newly-formed wholly-owned subsidiary of Shire ("Acquisition Sub")
would be merged with and into Roberts in a stock-for-stock exchange (the
"Merger"). Pursuant to the Merger, each outstanding share of common stock of
Roberts would be converted into the right to receive 3.4122 shares (the
"Exchange Ratio") of Shire Ordinary Shares of common stock (the "Merger
Consideration"). We understand that, unless the holders (the "Holders") of
Roberts common stock otherwise elect, Shire will provide Holders with one-third
of a Shire American Depository Share ("Shire ADS") for each Shire Ordinary
Share such Holder would be entitled to receive pursuant to the Exchange Ratio.
The Exchange Ratio shall be subject to adjustment as follows: i) if the Shire
ADS price (which shall be determined based on the average of the last reported
sale price per Shire ADS on the NASDAQ National Market over the fifteen
consecutive trading days ending on the third trading day immediately preceding
the consummation of the Merger) is less than $21.09, the Exchange Ratio will be
fixed at 3.8407; ii) if the Shire ADS price is between $21.09 and $23.73, the
Exchange Ratio will be determined by dividing $27.00 by one-third of the Shire
ADS price; iii) if the Shire ADS price is between $23.73 and $29.01, the
Exchange Ratio will be fixed at 3.4122; iv) if the Shire ADS price is between
$29.01 and $31.65, the Exchange Ratio will be determined by dividing $33.00 by
one-third of the Shire ADS price; and v) if the Shire ADS price is greater than
$31.65, the Exchange Ratio will be fixed at 3.1280. If Roberts terminates the
Merger for certain reasons, Shire will be entitled to (i) receive a termination
fee of $30 million from Roberts, and (ii) exercise an option to purchase up to
6,345,926 newly-issued shares of Roberts common stock at a price of $30.00 per
share in accordance with the terms of an Option Agreement (the "Option
Agreement") to be entered into by Shire and Roberts. If Shire terminates the
Merger for certain reasons, Roberts shall be entitled to receive a termination
fee of $30 million from Shire.

                                      C-1
<PAGE>

Shire Pharmaceuticals Group plc
July 23, 1999
Page 2

You have provided us with a draft of the Agreement and Plan of Merger (the
"Agreement") and a draft of the Option Agreement both dated July 23, 1999. We
understand that in conjunction with the Merger, Shire will be adopting U.S.
Generally Accepted Accounting Principles ("U.S. GAAP") as its primary
accounting standard. We further understand that the Merger will be accounted
for under U.S. GAAP as a pooling of interest.

You have asked us to render our opinion as to whether the "Exchange Ratio" is
fair, from a financial point of view, to Shire.

In the course of our analyses for rendering this opinion, we have:

    1. reviewed a July 23, 1999 draft of the Agreement and a July 23, 1999
       draft of the Option Agreement;

    2. reviewed Roberts' Annual Reports to Shareholders and Annual Reports
       on Form 10-K for the fiscal years ended December 31, 1997 and 1998,
       and its Quarterly Report on Form 10-Q for the period ended March 31,
       1999;

    3. reviewed certain operating and financial information, including
       projections, provided to us by Roberts' management relating to
       Roberts' business and prospects;

    4. met with certain members of Roberts' senior management to discuss its
       operations, historical financial statements and future prospects;

    5. reviewed Shire's Transition Report and Accounts on Form 20-F for the
       six months ended December 31, 1997, its Annual Report and Accounts on
       Form 20-F for the fiscal year ended December 31, 1998, and its
       interim results for the three months ended March 31, 1999;

    6. reviewed certain operating and financial information, including Wall
       Street equity research analyst projections that were adjusted by the
       senior management of Shire (the "Adjusted Shire Analyst
       Projections"), relating to Shire's business and prospects;

    7. met with certain members of Shire's senior management to discuss its
       operations, historical financial statements and future prospects;

    8. reviewed analyses provided to us by Shire's management relating to
       the anticipated financial performance of Roberts subsequent to the
       Merger;

    9. reviewed certain estimates of cost savings and other combination
       benefits expected to result from the Merger, prepared and provided to
       us by the senior management of Shire;

    10. reviewed the historical prices and trading volumes of the common
        stock of Shire and Roberts;

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<PAGE>

Shire Pharmaceuticals Group plc
July 23, 1999
Page 3

    11. reviewed publicly available financial data, stock market performance
        data and valuation parameters of companies which we deemed generally
        comparable to Shire and Roberts;

    12. reviewed the terms of recent acquisitions of companies which we
        deemed generally comparable to Roberts; and

    13. conducted such other studies, analyses, inquiries and investigations
        as we deemed appropriate.

In the course of our review, we have relied upon and assumed, without
independent verification, the accuracy and completeness of the financial and
other information, including without limitation the Adjusted Shire Analyst
Projections and the projections (in the case of Roberts), provided to us by
Shire and Roberts. With respect to Shire's and Roberts' projected financial
results and potential synergies that could be achieved upon consummation of
the Merger, we have assumed that they have been reasonably prepared on bases
reflecting the best currently available estimates and judgments of the senior
managements of Shire and Roberts as to the expected future performance of
Shire and Roberts, respectively. We have not assumed any responsibility for
the independent verification of any such information or of the projections
provided to us and we have further relied upon the assurances of the senior
managements of Shire and Roberts that they are unaware of any facts that would
make the information or projections provided to us incomplete or misleading.
In arriving at our opinion, we have not performed or obtained any independent
appraisal of the assets or liabilities of Shire and Roberts, nor have we been
furnished with any such appraisals. Our opinion is necessarily based on
economic, market and other conditions, and the information made available to
us, as of the date hereof. We have assumed that the Merger (i) will qualify as
a tax-free "reorganization" within the meaning of Section 368(a) of the
Internal Revenue Code of 1986, as amended and (ii) will be accounted for as a
pooling of interests under U.S. GAAP.

We do not express any opinion as to the price or range of prices at which the
Ordinary Shares or ADSs of Shire may trade subsequent to the consummation of
the Merger.

We have acted as a financial advisor to Shire in connection with the Merger
and will receive a fee for such services.

Bear Stearns acted as lead managing underwriter on Shire's public offering of
Shire ADS's in March 1998. In the ordinary course of business, Bear Stearns
may actively trade the equity securities of Shire and Roberts for its own
account and for the account of its customers and, accordingly, may at any time
hold a long or short position in such securities.

It is understood that this letter is intended for the benefit and use of the
Board of Directors of Shire and does not constitute a recommendation to the
Board of Directors of Shire or any holders of Shire's Ordinary Shares as to
how to vote in connection with the Merger. This opinion does not address
Shire's underlying business decision to pursue the Merger. This letter is not
to be used for any other purpose, or reproduced, disseminated, quoted or
referred to at any time, in whole or in part, without

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Shire Pharmaceuticals Group plc
July 23, 1999
Page 4
our prior written consent; provided, however, that this letter may be included
in its entirety in any proxy statement / prospectus to be distributed to
holders of Shire Ordinary Shares or ADSs or Roberts Common Stock in connection
with the Merger.

Based on and subject to the foregoing, it is our opinion that the Exchange
Ratio is fair, from a financial point of view, to Shire.

Very truly yours,

BEAR, STEARNS & CO. INC.

         /s/ Steven R. Frank
By: _________________________________
      Senior Managing Director

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