18/07/2016 11:57 BST | Updated 19/07/2017 06:12 BST

Why the Trident Vote Is a Masterclass by the New PM

The Trident vote is a smart bit of work by the new PM - a chess move on the board of Westminster that signals what we can expect from Theresa May in the coming years.

The Trident vote is a smart bit of work by the new PM - a chess move on the board of Westminster that signals what we can expect from Theresa May in the coming years.

With the party still staggering from EU in-fighting, focusing immediately on a contentious issue like investing in nuclear weapon capability shifts the attention to the divides and potential areas of instability in the opposition.

First up, it wrenches apart the Labour Party still further. Jeremy Corbyn is a lifelong supporter of unilateral nuclear disarmament, and previously voted against, but many in the parliamentary Labour party don't share his view. Corbyn has said he'll offer Labour MPs a 'free' vote - but since he received a vote of no confidence last week, it's unlikely that many Labour MPs will listen to take his lead on the issue seriously. At the same time, 19 Labour MPs in the 2010-2015 parliament voted for the SNP-Plaid Cymru motion to scrap Trident, and so it's likely some Labour MPs will vote against Trident again in this more significant debate. Generally, Corbyn and Labour's planned policy of renewing the submarines but removing the nuclear deterrent doesn't do anything for them. In an Ipsos/MORI poll, the plan was supported by only 28% of the public.

The debate on Trident goads the SNP into a reaction against the Conservatives, which has the potential to unsettle SNP support in Scotland. Although most think the Scots are opposed to renewing Trident, in fact a poll for STV in February this year showed more of a mixed picture. 40% of all Scots want to retain nuclear weapons and 9% are not sure. It's only among SNP voters that support for removing the nuclear deterrent reaches 72%.

A high profile vote on a divisive topic like this, so early in the PM's term, looks risky. The previous vote looked conclusive. 364 votes against the motion to scrap Trident against and 37 for. And of those who voted to scrap Trident, 12 or so have now left parliament. But this vote is very different, not an opportunity for a protest vote, but Government commitment and heavy expenditure. The vote against Trident will be substantially increased since the January 2015 vote, when only 5 SNP MPs voted against. Given their larger representation in the House of Commons now, they are more likely to get perhaps all 56 voting against.

But May knows there's going to a comfortable majority that will deliver an important quick win in terms of uniting her own party and setting a tone of confident decision-making. Most Tories (with the exception of Crispin Blunt - if he hasn't changed his mind in this new political context) will vote for renewal. So if we assume Caroline Lucas plus the three Plaid Cymru MPs and all SNP MPs vote against, with another perhaps 15-20 Labour MPs and maybe up to five Liberal Democrats, that means a vote against Trident numbering around 90-110 versus around 350-400 backing investment in Trident, and the remaining MPs abstaining.

With so much uncertainty, the vote is important for sending a clear signal about the kind of leader May plans to be. The comparisons with Margaret Thatcher are obviously too easy and spurious, but there's no doubt May wants to show she's not backing away from anything, outward-looking, tough and ready to make important long-term decisions. Trident is a piece of post-Brexit good news for the economy and employment. 2,200 people are currently employed working on Trident in the MOD, BAE Systems, Babcock International and at Rolls-Royce. When manufacturing starts, it will employ 6,000 people, involving around 850 companies across the supply chain. We've already spent £2bn on the programme. So to scrap it now would be a huge sunk cost. The steel for the four submarines is already ordered too and would add further costs if scrapped.

Going ahead with Trident, as set out by the 2010 Strategic Defence and Security Review, means the UK would move to 120 operationally available nuclear warheads by 2020 and that compares with the 520 we had at the peak of tensions during the Cold War. So go-ahead for Trident is a loud and clear message for any potential adversaries such as Russia (with its constant UK airspace-buzzing). Symbolically - and whether you're comfortable with the implications or not - nothing says security more to the general public than the nuclear deterrent.