“If the [claimant] were negligent but his negligence was not a cause operating to produce the damage there would be no defence. I find it impossible to divorce any theory of contributory negligence from the concept of causation.” 1097 Thirdly, a key point (which is common ground) is that it is necessary when applying section 1(1) of the 1945 Act, to take account “both of the blameworthiness of the parties and the causative potency of their acts” (Jackson v Murray, supra at [40]). The consequence of this is that “[f]ault not causally contributing to the damage cannot be taken into account in the first place” for the purposes of assessing apportionment (see McGregor on Damages (20th edn.) at 7-009).”