Dr Julian Lewis: If a decision to reduce the number of warheads on a Trident missile would result in cost savings?

[SUPPLEMENTARY:] I am in no way asking the Secretary of State to pre-judge the findings of the strategic defence review, but I am asking whether it is physically possible for the number of warheads on a Trident missile to be reduced without massive cost. Is he aware that, the last time an incoming Labour Government cut the warhead potential of the deterrent – that was the Wilson Government in the 1960s – and cut it for similar political reasons, it was necessary to introduce the Chevaline project to multiply the number of warheads, which added 60 percent to the cost of the entire system? Can he promise us that the same sort of mistake will not be made again for doctrinal reasons?