Court case[1951] 2 KB 861

A county council employed contractors (the defendants) to carry out excavation work on land belonging to the council. In the course of the work their mechanical excavator struck and damaged an electric cable belonging to the plaintiffs, the National Coal Board, which ran under the land. The cable had been laid many years before; it was not marked on any map, and neither the council nor the contractors knew, or could reasonably have known, that it was there. Water entered the damaged cable and caused an explosion, and the plaintiffs sued for the damage in trespass and negligence.

The Court of Appeal held that neither the council nor the contractors was liable. They had not been negligent, since they had no reason to suspect the presence of the cable and could not have discovered it by reasonable care. The damage was unintentional and was the result of an inevitable accident; an involuntary and non-negligent act does not amount to a trespass to goods. The Court distinguished a voluntary act directed at another's property from an interference of which the actor is wholly and reasonably unaware; the latter, done without negligence, is not actionable. The plaintiffs' claim therefore failed.