High Court Approved Judgment
Martlet v Mulalley
285. They gave a number of examples, the first being that “given by Hart and Honore in their seminal
treatise on Causation in the Law, 2nd ed (1985), p 206 of a case of two fires, started independently of
each other, which combine to burn down a property”. They observe that this is a class of case where
"each putative cause, although not necessary, was on the assumed facts sufficient to bring about the
relevant harm”. They distinguish this from the “further class of cases in which a series of events
combine to produce a particular result but where none of the individual events was either necessary or
sufficient to bring about the result by itself, giving as their last example where multiple polluters
discharge hazardous waste into a river where the waste discharged by each would not be necessary or
sufficient to cause the harm by itself.
286. Coulson J addressed the same subject in his judgment in Greenwich Millennium Village Ltd v Essex
Services Group plc [2013] EWHC 3059 (TCC) at [171] and following. He said that the court should
not depart from the “but for” test without clear and proper reasoning. He gave the same two examples.
He said that the authorities showed that in cases where there were two, concurrent, independent causes
of the loss, fairness and reasonableness might dictate that the but for test should not be required to be a
necessary condition. He referred to other cases where two causes give rise to the loss but where each,
on its own, would not have done so where, by reference to authority, that was sufficient to establish
liability. The case he cited, the decision of Devlin J in Heskell v Continental Express [1950] 1 All ER
1033, was also cited in the FCA case at [172] for the proposition that “if a breach of contract is one of
two causes, both co-operating and both of equal efficacy, it is sufficient to carry judgment for damages”.
287. In cases where it is not appropriate to apply the but for test, it is sufficient for the claimant to succeed
so long as event X is an effective cause of event Y. This was the question which Fraser J posed himself
in the Beattie v Canham case, with which I began this discussion.
288. The answer to the question which test to apply may be influenced - and I consider is influenced in
this case - by the question as to what is the loss which is the subject of the enquiry. The defendant
suggests that the loss is the cost of the replacement of the cladding which the claimant is seeking to
recover. However, in my judgment, that is looking at the case from the wrong starting point. As the
claimant submitted, the proper measure of damages is diminution in value, even if measured by the
reasonable cost of repairs: see Coles v Hetherton [2013] EWCA Civ 1704 per Aikens LJ giving the
judgment of the court at paragraphs 27 - 28. In a typical construction case such as the present that will
be the cost of the works necessary to reinstate or repair the defective work.
289. This is borne out by the comprehensive analysis undertaken by HHJ Peter Coulson QC, sitting as a
High Court Judge, in McGlinn v Waltham Contractors Ltd & others [2007] EWHC 149 (TCC). The
facts of the case are irrelevant for present purposes, save to note that it had the same essential similarity
as the present case that the claimant was claiming the cost of entire removal and replacement (in that
case, of a very substantial house), whereas the defendants were contending that he should be limited to
the costs of rectification. At [787] the judge noted that whilst, traditionally, the measure of damages is
diminution in value, in construction cases more usually the appropriate measure is the cost of
reinstatement or repair as the foreseeable consequence of the defective work. At [802] he agreed with
the claimant’s submission that there was no difference in principle between the claimant’s primary
claim for the cost of demolition and rebuilding and the secondary alternative claim for the costs of
repair. At [803] he concluded that it followed that the claimant was entitled to recover the cost of repair,
if that was all the court found he was entitled to, notwithstanding that in fact repair was no longer
practicable because the property had already been demolished.
290. The decision of the Court of Appeal in County Ltd v Girozentrale Securities is also relevant in this
case when one considers the two causes which, on the hypothesis with which I am now concerned, are
in play. The cause asserted by the claimant is the presence of the installation breaches for which the
defendant is legally responsible. The cause alleged by the defendant is the claimant’s decision to
replace as a result of the change in the fire-safety regime coming into force after it had completed the
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