McGhee v National Coal Board  1 WLR 1
To satisfy causation, a claimant need only prove that the negligent behaviour most likely made a material contribution to the injury.
The claimant, McGhee, contracted a skin condition (dermatitis) in the course of his employment with the defendant, the National Coal Board. The defendant requested McGhee work with the brick kilns, but failed to satisfy their statutory duty to provide a washing area to allow employees to remove the dust from the kilns at the end of the day. Subsequently, employees could not wash off the dust till they returned home.
Two possible causes were identified for McGhee’s dermatitis: exposure to brick dust during the working day, and the continued exposure received between the end of the day and being able to wash at home.
Could the defendant be found liable for the claimant’s injuries, or, as the defendant’s asserted, could the chief relevant authority of Bonnington Castings Ltd v Wardlaw  AC 613 be distinguished on the grounds that it could not be ascertained whether every skin abrasion of the claimant’s exposed to the brick dust was responsible for his contracting dermatitis, whilst in Bonnington Castings it had been determined that all the harmful silica breathed by the claimant had contributed to his injury.
The House of Lords held that the instant case ought not be distinguished from Bonnington Castings; the claimant did not need to prove that all of his abrasions and their exposure to brick dust had contributed to his illness, but rather that the dust exposure stemming from the defendant’s negligent breach of statutory duty had, on the balance of probabilities, materially increased the likelihood of him developing dermatitis.