Dr Julian Lewis: It is an open secret that the Ministry of Defence wanted this debate to take place in the spring, so I do not blame the Secretary of State for the fact that it has not happened. However, he is on record as saying that people are worried about the wavering position of the Labour Opposition on this matter. Would it not assist us to restore bipartisanship to the issue if the debate were to be brought forward, at least to before the Labour party’s conference, or do the Government – by which I mean No. 10 – prefer dissension at a Labour party conference to bipartisanship on a particularly important issue?

[The Secretary of State for Defence (Michael Fallon): Well, no. The position is that in November we announced our commitment to replacing the existing four Vanguard submarines, and we would like that principle to be endorsed by a vote in this ​House.  I would obviously like that vote to take place as soon as possible, respecting of course the periods of purdah that will exist this spring and summer.]