The Prime Minister will open a Commons debate on Trident renewal with a warning not to abandon the UK’s “ultimate safeguard” out of a sense of “misplaced idealism”.
MPs vote tonight on whether to replace the four Vanguard-class submarines based at Faslane on the Clyde that carry the UK’s warheads, with one vessel at sea around the clock prepared to launch a nuclear strike.
A government motion supporting renewal is expected to pass, with a large number of Labour MPs set to join the Conservatives in backing it. However, 58 of Scotland’s 59 MPs will oppose the motion, including the entire SNP group at Westminster.
Angus Robertson, said the voice of “great swathes of civic society in Scotland” was being “drowned out by petty party politics”.
The SNP have called for the vote to be postponed until the “unprecedented turmoil” in the wake of the EU referendum has passed.
“Today’s vote on Trident is one of the most important that this Parliament will ever take,” Mr Robertson said.
“For the Tories to commit to spend hundreds of billions of pounds on weapons of mass destruction – particularly at a time when they are making significant cuts to public services – would be morally and economically indefensible.”
Ian Murray, the sole Labour MP in Scotland, pledged to vote against Trident when he was elected in 2010, while Liberal Democrat Alistair Carmichael does not support a like-for-like renewal of the weapons and has said he will oppose the motion.
The Prime Minister is expected to open the six and a half hour debate by saying: “It is impossible to say for certain that no extreme threats will emerge in the next 30 or 40 years to threaten our security and way of life. And it would be a gross irresponsibility to lose the ability to meet such threats by discarding the ultimate insurance against those risks in the future.”
Mrs May will conclude: “We cannot compromise on our national security. We cannot outsource the grave responsibility we shoulder for keeping our people safe.
“And we cannot abandon our ultimate safeguard out of misplaced idealism.
“That would be a reckless gamble: a gamble that would enfeeble our allies and embolden our enemies. A gamble with the safety and security of families in Britain that we must never be prepared to take.”
The former assistant chief of the defence staff responsible for the UK’s nuclear deterrent told Scotland on Sunday it was a “massive gamble” to hold a vote on Trident while Scotland’s future in the UK remains uncertain.
Rear Admiral John Gower said that if a future Scottish Government demanded closure of the Faslane base, “that is the end of the deterrent”.
He said: “The investment in replacing Trident, based on the UK being a nuclear state well into the 2060s, if not the 2070s, is a massive gamble.
“It’s a massive bet based on Scotland staying in the Union come what may for the best part of 40 to 60 years.”
The Ministry of Defence confirmed last week it was not drawing up any plans to relocate Trident away from Faslane in the event of Scottish independence.
Labour’s shadow foreign and defence secretaries have urged the party’s MPs to abstain, claiming the vote has been scheduled to “sow further divisions” because renewal was greed in principle in 2007.
However, deputy leader Tom Watson said abstaining would be an “abdication of responsibility”.
Leadership candidate Owen Smith has committed to supporting renewal while leader Jeremy Corbyn is expected to vote against, with Labour whips giving MPs a free vote.