Trident: We all need to have a rethink on Britain's nuclear weapons

Do you know what you think about Trident? Most of us have a settled view of the country’s nuclear weapons: either we think that we should keep them while other countries have them, or that they are a poor use of money for weapons that could never be used. This might be a good time, however, for everyone to think again.

We are approaching a vote in the House of Commons on building the next generation of submarines. These are needed if the UK wants to keep nuclear missiles continuously at sea so that they are always a deterrent against possible nuclear-armed enemies.

MPs have already voted, in 2007, to do the early work on what is now known as the Successor programme. That vote was carried comfortably, although a quarter of Labour MPs and all the Liberal Democrats, then 62 strong, voted against. The plan was then to hold a further vote, around now, on what was called the “main gate” decision, the point at which the main contracts start to be signed. However, the Ministry of Defence has opted for a more gradual build-up, and so the vote is more a matter of politics than of civil engineering.

Nor, to be blunt, is there much doubt about the outcome. Opinion among Labour MPs has swung against Trident over the past nine years. The leader and the Shadow Chancellor are opposed. But the deputy leader and most of the Shadow Cabinet still support it, as do about half of all Labour MPs. The Lib Dems have been replaced by the Scottish National Party as the second largest group of MPs opposing nuclear weapons. But the Conservatives, with a few exceptions, are solid supporters, and they have a majority to start with.

However, this means it ought to be possible to have a considered debate: both sides need not feel they have to raise the rhetorical temperature to try to influence a finely balanced result. The other reason this might be a good time for rethinking the case for Trident from first principles is technological change. The Independent on Sunday reported two months ago the concerns of some defence analysts that underwater drones might make it hard to hide nuclear submarines in the oceans, thus weakening the deterrence theory.

This was a point made by Emily Thornberry, the shadow Defence Secretary, at a meeting of Labour MPs this month. They were not, on the whole, much impressed. Their scepticism is understandable. If Ms Thornberry does not believe in nuclear deterrence, she should make that argument. If underwater drones weaken the effectiveness of a submarine-based deterrent, the implication is that the UK should consider putting its nuclear missiles on aircraft instead.

On the other hand, Ms Thornberry did not deserve the mockery to which she was subjected. Underwater drones could pose a challenge to the credibility of the British deterrent in years to come, as we report today. Ms Thornberry may not be the best person to ask the question, but somebody ought to be asking it.

On Saturday, Jeremy Corbyn repeated his opposition to Trident at a Campaign for Nuclear Disarmament rally in Trafalgar Square. He was elected to the Labour leadership as a unilateral disarmer. He is right to speak up for what he believes, and he is entitled to try to change the party’s policy on the subject. But he needs to think more about how to persuade the voters. As our ComRes poll found recently, it does not matter how you ask the question, most of the British people want to keep the Bomb.

Equally, however, those who believe that nuclear weapons are an insurance in an uncertain world ought to ask whether a submarine-based system is likely to remain effective for the next quarter-century. Both sides in this debate need to open their minds to new thinking.