From Law wiki, the wiki for law research

This case (Photo Productions v Securicor Ltd [1980] ALL ER 556) has, so far at least, put paid to the idea that an Exclusion clause is nullified in a significant breach of contract. A number of cases defined this principle, of which the best known is Harbutts plasticine v wayne tank (1970). The decision in Harbutt's is overruled by Photo Productions.

The facts of the case are as follows, and were not disputed. PP contracted S to provide a night watchman for their factory. One might the watchman set fire to the factory and destroyed it. In its defence, Securicor relied on an exclusion clause disclaiming liability for damage caused by its employees. On the principles of Harbutt's it could be argued that a watchman's setting fire to the building he was watching was a fundamental breach of contract, which would invalidate the exclusion clause. However, the House of lords ruled unanimously that the exclusion clause should stand. Between organization with rough parity of bargaining power, it was confirmed, the contract must be interpreted on the basis of the intentions of the parties.

The facts of the case are not all that different from those in the later case of Phillips Products v Hyman (see: Phillips products v hyland (1987)), but in the latter the exclusion cause was struck down. Why should this be? The Phillips case was fought under the Unfair contract terms act (1977); the defence there was that the exclusion clause was not invalidated by non-incorporation, but by being unfair in the terms of the Act. It is not clear (to me, at least) whether Photo Productions could have been fought the same way.