(2) what assessment he has made of (a) whether Vanguard submarines have typically operated (i) at a higher level of intensity and (ii) for longer periods at sea than United States Ohio-class Trident submarines and (b) the effect of those factors upon the differential in-service lives of those submarines.
[holding answer 11 December 2006]: I refer the hon. Member to paragraphs 1-4, 5-6 and 6-5 of the White Paper, ‘The Future of the United Kingdom's Nuclear Deterrent’ (Cm 6994), published on 4 December 2006.
When detailed concept work begins on a new class of SSBNs, we will take into account relevant lessons from the submarine-building experience of other countries, including the United States, as we would normally do on a programme of this kind.
[holding answer 11 December 2006]: As the Government stated in the White Paper, ‘The Future of the United Kingdom's Nuclear Deterrent’ (Cm 6994), published on 4 December 2006, we expect that continuous deterrent patrols could no longer be assured from around 2024 if the first of the new submarines were not in place by then.
The White Paper made clear that we are not yet in a position to make a firm judgment about how many submarines we require in future. It is too early to determine subsequent in-service dates.