WESTMINSTER has voted to replace Trident as the SNP leadership suggested the controversial decision would accelerate the move towards Scottish independence.

During a debate lasting almost six hours, Theresa May claimed it would be an "act of gross irresponsibility" if the UK Government were to discard Britain’s fleet of Clyde-based submarines and warned that the country would be taking a "reckless gamble" if it relied on other nations for its protection.

READ MORE: MPs vote in favour of renewing Trident nuclear weapons system by 472 votes to 117

Describing the nuclear deterrent as the “ultimate insurance,” the Prime Minister, speaking from the Commons despatch box for the first time in her new role, launched a veiled attack on Labour leader Jeremy Corbyn by claiming some Opposition frontbenchers appeared to be the first to "defend the country's enemies" and the last to accept what the UK needed to protect itself.

The Conservative Government won the vote comfortably with 472 votes to 117, a majority of 355.

Labour divisions were laid bare with its vote split three ways with some of its MPs voting for, some against and some abstaining; a majority 138 voted to replace Trident.

READ MORE: MPs vote in favour of renewing Trident nuclear weapons system by 472 votes to 117

Meanwhile, all 54 SNP MPs opposed the motion. Indeed, of Scotland’s 59 MPs, only one, David Mundell, the Scottish secretary, voted for replacing the nuclear submarine fleet at Faslane.

When challenged in the debate by SNP backbencher George Kerevan if she would be willing to press the nuclear button, which, he said, could kill 100,000 innocent people, Mrs May replied: “Yes.

“The whole point of a deterrent,” she insisted, “is that our enemies need to know that we would be prepared to use it, unlike the suggestion that we could have a nuclear deterrent but not actually be willing to use it, which seemed to come from the Labour front bench.”

READ MORE: MPs vote in favour of renewing Trident nuclear weapons system by 472 votes to 117

Mr Corbyn, a long-standing member of CND, reiterated how he would not be prepared to press the nuclear button, telling MPs: "I do not believe the threat of mass murder is a legitimate way to go about dealing with international relations."

Angus Robertson for the SNP denounced Trident as an “immoral, obscene and redundant weapons system,” which the Scottish people had repeatedly, clearly and consistently opposed.

Noting how Scotland had also voted to remain in the EU, he argued that it was “not a normal situation for the state to totally disregard the wishes of the people and this Government has a democratic deficit in Scotland, and with today's vote on Trident it's going to get worse, not better”.

READ MORE: MPs vote in favour of renewing Trident nuclear weapons system by 472 votes to 117

The SNP leader at Westminster added to cheers from his colleagues: "It will be for the Scottish people to determine whether we are properly protected in Europe and better represented by a government that we actually elect; at this rate, that day is fast approaching."

Mr Robertson also repeatedly pressed Mrs May on how much the new submarine fleet would cost in total over its lifetime.

While the PM explained how replacing the Vanguard submarines would cost £31 billion with a £10 billion contingency fund, the Nationalist leader pressed her on the annual maintenance costs and said, that without the full information, she was asking MPs to sign a “blank cheque”.

Tory MP Crispin Blunt, who chairs of the Commons foreign affairs committee, intervened to say he had estimated, based on a running cost of six per cent of the defence budget, that the new fleet would cost up to £179bn in total to renew and run Trident for the next 32 years.

Meanwhile, the deep divisions within Labour over replacing Trident were exposed with just 48 of their 230 MPs following leader Jeremy Corbyn's plea to vote against the motion.

Its MPs reacted with fury after Mr Corbyn referred to the party's current policy of being in favour of renewing the nuclear deterrent in the past tense, stressing how it was under review.

But ahead of the debate, the GMB leader Tim Roache insisted the party leader should abide by existing Labour policy to support replacing Trident, warning how 45,000 jobs around the UK were dependent on the programme going ahead.

With Mr Corbyn facing a leadership challenge from Angela Eagle and Owen Smith, Mr Roache said he would now be balloting his 640,000 members on whether they believed the Islington MP was still the right person to lead the party.

His comments came as Labour's deputy leader Tom Watson warned of "consequences" for trade union bosses such as Unite general secretary Len McCluskey, who continues to back Mr Corbyn.

Mr Watson said: "You have Len McCluskey strongly supporting Jeremy Corbyn, who will be voting against the Trident programme tonight, which will put many defence workers in Unite out of their jobs if he gets his way.

"If I was a defence worker in Unite and I was reading social media that Unite were about to give Jeremy Corbyn a quarter of a million pounds of my subscriptions, I would be furious," he added.