[The Secretary of State for Defence (Grant Shapps): … There is no more important element of defence than our nuclear deterrent. Again, it is good to hear that both sides of the House now seem to back the nuclear deterrent, but that cannot be done without backing the money to support it.]

Sir Julian Lewis: It is true that both sides of the House strongly back the nuclear deterrent at the moment, if my right hon. Friend is talking about the Labour Opposition. However, with recent talk of the prospect of a hung Parliament, one could find oneself in the same situation as the Cameron Government in 2010, when the right hon. Member for Warley (John Spellar) and I were begging for a vote to be held to renew the nuclear deterrent, but because of the coalition deal with the Liberal Democrats, that vote was postponed, at great expense, for four years until 2016. We would like to hear assurances from both Front Benches that no such situation will ever be allowed to arise again.

[The Secretary of State for Defence (Grant Shapps): I am pleased to reassure my right hon. Friend from this Front Bench that no such delay would be countenanced. Just in the last few weeks we have issued the defence nuclear enterprise Command Paper – [Interruption.] I thought the Opposition Front Bench knew that there was a coalition Government, but perhaps they missed it. Perhaps they also missed the point that my right hon. Friend was making.

Richard Foord {Liberal Democrat Defence Spokesman}: I am grateful to the Secretary of State for giving way, and I can offer him the assurance that the Liberal Democrats embrace the continuous at-sea deterrent with four submarines. What is more, the strategic environment in which we were operating in 2010 was very different from that which we see today: the Liberal Democrats made the right call then, and we have made the right call now.

Grant Shapps: You heard it here first, Madam Deputy Speaker. I warmly welcome that commitment, which was not available under the then coalition Government. It is an important moment, and I welcome that commitment from the hon. Gentleman, as I welcome it from Labour.

I gently remind the House that 11 Opposition Front Benchers have voted against the deterrent in their time here, including three members of the current shadow Cabinet, including the shadow Foreign Secretary, the shadow Levelling Up, Housing and Communities Secretary, and the shadow Deputy Prime Minister. The House is right to ask, and the country will want to know, whether that commitment is as firm as we now hear it is from the Liberal Democrats. It will also want to know, even if the commitment is said to be firm, whether Labour is prepared to fund it. Again, it comes back to the 2.5%.

John Spellar: Can we be clear that, as was kindly referenced by the right hon. Member for New Forest East (Sir Julian Lewis), that situation was the result of a failure of political judgment and will by David Cameron? He could have said to the Liberal Democrats, “This is a matter of strategic national interest. If you don’t like it, you can give up your jobs and walk out of the Government.” They would have bottled it. The fact was that we lost six years and a huge amount of money, and we are putting CASD at real risk with enormously elongated tours of duty for our tremendous submariners.

Grant Shapps: The right hon. Gentleman wants to relitigate the past, but I think we all agree that we cannot do anything about it. I want to talk about the future, and the future is that those on his own side have yet to commit to the 2.5% that is required to ensure that our nuclear deterrent can deliver on time. In March the Prime Minister and I published the defence nuclear enterprise Command Paper, setting out our long-held and unshakeable commitment to our own independent nuclear deterrent.

Mark Francois: I appreciate my right hon. Friend’s desire to look forward rather than back but, just for the record, does he remember, as I do, that at one point the Liberal Democrat policy on Trident was to maintain the submarines but to send them to sea without any missiles?

Grant Shapps: I will be as diplomatic as possible: the Liberal Democrats asked us to investigate a range of options, and I am very pleased that the one we ended up with was the four-submarine continuous at-sea deterrent.

We are investing £41 billion in our next generation of the Dreadnought fleet, and investing in our replacement UK sovereign nuclear warhead as well. … ]

[For Julian's speech in this debate click here.]