He was enjoying a drink on the balcony, which was accessible via a lockable sliding door, when it unexpectedly locked upon closing. For 30 minutes he tried to attract attention without success (although admittedly not shouting too loudly as it was late at night) and so he attempted to step across onto the balacony of the adjacent room, which his family also occupied. He stepped onto a ledge underneath the balcony and it gave way causing him to fall and fracture his skull.
At trial the locking mechanism was found to have been defective. However, the claim failed on causation. The judge found Mr Clay had committed a new and independent act, in circumstances which presented no emergency or threat, and so being locked out was part of the background rather than a sufficiently proximate cause of the accident. By a majority the Court of Appeal upheld the decision.
An intervening act must be so unreasonable as to eclipse the defendant’s wrongdoing. The bar is set very high: it must go beyond contributory negligence and it must be something “utterly unreasonable” (McKew v Holland  3 All ER 1621).
Moylan LJ dissented and said that the judge’s evaluation was too narrow. He thought it must have been reasonably foreseeable that Mr Clay might sustain injury as a result of being trapped on the balcony and attempting to escape. At trial it had been suggested that Mr Clay ought to have broken the glass in the door to gain access to the room, an act which would have certainly given rise to a risk of injury.
Such cases are fact-sensitive, but it is somewhat difficult to reconcile this case with one such as Sayers v Harlow UDC  1 WLR 623, where the claimant became locked in a public lavatory and, after 15 minutes of trying to attract attention, she suffered injury after slipping while trying to climb over the door. There the defendant was held liable (with a finding of 25% contributory negligence). What marked Mr Clay’s actions as sufficiently foolhardy though was the fact that the life-threatening danger in trying to escape far outweighed the inconvenience of finding himself on locked out on the balcony.