Dr Julian Lewis: Members of the Scottish National Party have been licking their lips in public at the prospect of blackmailing one of the two main parties into delaying or abandoning the replacement of the Trident submarines. Will the Prime Minister confirm that if he is still Prime Minister in 2016, as he should be, he will ensure that the maingate contracts for four successor submarines are signed that year?

[The Prime Minister: I can reassure my hon. Friend. For me, Trident and its replacement are non-negotiable. They are an absolutely vital part of this nation’s security. Let me just remind Labour Members of the leaflet going out across Scotland. It says this:

“At the General Election we need to stop the Tories being the largest party.”

They have given up trying to be the Government and trying to win a majority. They want to crawl into Downing street on the coat tails of the SNP and put our country at risk. The British people will never have it.]