Knightley v. Johns [1982]

If a whole sequence of events is a natural and probable consequence of a tortfeasor's negligence and therefore reasonably foreseeable, none of the events in the sequence can be regarded as a novus actus interveniens; negligent conduct is more likely to break the sequence than non-negligent conduct, and positive acts more likely than inaction. D, due to his own negligence was involved in a traffic accident by the exit of a tunnel carrying one-way traffic with a sharp bend in the middle. I, the police inspector in charge forgot to seal off the tunnel, and sent P, a motorcycle policeman, back through the tunnel on his motor-cycle against the traffic to remedy the omission. This manoeuvre was in breach of police-force standing…