P was injured and taken to hospital where there was a negligent failure to treat him. He later developed a more serious injury from the initial one, and the trial judge found that there was a 25% chance that if P had been treated on time the latter injury would have been prevented. The trial judge had awarded him 25% of the value of his injury. HL reversed this and held that it was for P to prove on the balance of probabilities that the negligence of D caused his later more serious injury. Since he had not, his claim for that injury was dismissed.
Lord Bridge: since, if P proved on the balance of probabilities (i.e. 51%) that the negligence caused his injury, he would be entitled to the full amount and not merely 51% of it. Therefore it would be unjust to make D pay a proportion of this where he had not reached the evidentiary threshold.