Palmer v Nightingale (t/a Andover Pest Control)

In a competing-theories causation case, the court may analyse and eliminate possible causes. It must nevertheless stand back and decide whether the claimant’s explanation is more likely than not to be correct. The court must not select the least improbable explanation where all competing explanations remain improbable. A defendant is not negligent merely because subsequent testing shows that a product was capable of causing harm, if the product information reasonably indicated that it was non-flammable and the defendant acted in accordance with accepted methodology. On the facts, placing rodent bait blocks about two or three inches from halogen lamps was reasonable. The claim therefore failed on liability and, alternatively, on causation.

The claimant, owner of Mead House, claimed damages for fire damage allegedly caused by the defendant pest controller’s negligent placement of rodent bait blocks near halogen downlighters. The defendant denied negligence and disputed causation.

The court found that access through the light fittings was an accepted method, but that the bait blocks had been placed on insulation or boards about two or three inches beyond the openings. The central issues were whether that method of placement was negligent and whether the bait blocks probably caused the fire.

1. Liability. The agreed methodology of accessing an otherwise inaccessible roof void through the light fittings was reasonable. The defendant had not placed the bait blocks touching or almost touching the lamps. Placing them about two or three inches beyond the openings was a reasonable course in the circumstances.
2. The bait blocks were described in the product information as non-flammable and as not containing combustible liquids. Although later testing showed that they could be ignited by a flame, the defendant could not reasonably be criticised for failing to anticipate that result. The warning concerning hot surfaces was properly understood as addressing the integrity of the product, not a particular fire risk.
3. The further criticisms concerning written risk assessments, removal of bait, and wiring the blocks did not establish negligence or breach of contract. The defendant was neither negligent nor in breach of contract.
4. Causation. Where several possible causes exist, the court may systematically analyse and eliminate them. It must then stand back and ask whether the claimant’s proposed explanation is more likely than not to be true. It is impermissible simply to select the least improbable cause where the alternatives remain improbable.
5. The fire probably originated in the roof void above the north-eastern bedroom. The incorrect halogen lamps generated excessive heat backwards into the roof void. The most likely material ignited was the insulation, with insect detritus and roof timbers as lesser possibilities. The bait blocks were a nugatory or theoretical possibility. Testing repeatedly failed to produce ignition, and the evidence did not establish that smouldering bait blocks had caused other materials to ignite.
6. The claim was dismissed. Alternatively, even if there had been negligence or breach of contract, causation was not proved.