15/06/2016 13:12 BST | Updated 16/06/2017 06:12 BST

For the Labour Party, Trident Would Be a Curious Hill on Which to Die

Jeremy Corbyn, vice-president of CND, must surely have spent much of his political life preparing for a fight over Trident. It would be understandable for him to think the moment for that fight has come. To save his party, he may have to think again.

After crushing defeat in 2015, the Labour Party was always likely to be facing a long road to recovery, and the election of Jeremy Corbyn, a leader at odds with his MPs, has made the process especially acrimonious. To stand a decent chance of returning to power, the party will need to pick its internal battles carefully. But after Corbyn's high-profile declaration that he would never use nuclear weapons, and with a defence-policy review ongoing, there are signs that the next big fight, post-EU referendum, will be about the renewal of Trident. If so, Labour could be making a big mistake.

In the first place, the divisions on this issue are so wide, the issue so historically toxic, that the debate may be irresolvable. If Labour MPs are whipped to oppose the renewal of Trident, the party could split badly. And this would not be any kind of catharsis. If a vote on Trident is the trigger for a coup against Jeremy Corbyn by Labour moderates, they will have chosen a curious hill on which to die. The party membership is probably against them, and while the broader electorate is probably with them, they are not with them by very much, nor with any great enthusiasm.

If the party leadership think this works to their favour, however, they should reconsider. In the first place, it is not clear that if this debate is held again, it will reach a different answer. The Labour government made the case for Trident renewal in a 2006 white paper, and Parliament approved it, by a comfortable margin, in March 2007. The coalition came to power in 2010 agreeing to disagree, but in 2013 a Lib Dem-led Cabinet Office review concluded, albeit controversially, that Trident was the best option after all. An eminent cross-party committee convened by a disarmament NGO came to a similar answer. Why should Labour expect this argument to go differently if it is held for a third time? The Conservatives have a majority in Parliament, preparatory work on the submarine-replacement project has long since started, and the real construction will start very soon. It is right for major strategic decisions to be properly scrutinised. But in practical terms, the battle is nearly over.

Admittedly, the practical aspects may not be enough to persuade the ideologically committed. In that case, they could consider this: the national political conversation has very limited bandwidth, and there is an opportunity cost to time spent on internal rows. Labour's left has a once-in-a-generation chance to shift the national centre ground on economics and public services. Labour's right has a do-or-die challenge to prove that the Blair/Brown project was not just about winning elections, but about making social democracy Britain's mainstream political language. Both sides will face a very uncertain landscape after the referendum, whatever the result. And neither side has a hope of its message reaching voters if Labour, to borrow David Cameron's phrase, is 'banging on' about Trident the way the Conservatives still bang on about Europe.

So what is to be done? If the Labour leadership try to compel the party's moderate wing to vote against the renewal of Trident, things will get ugly. As it happens, it looks like they may not be in a position to do so. In last year's defence review the government scrapped the idea of a 'main gate' decision on renewal, and promised a vote on a different question, centred around 'the principle of continuous at-sea deterrence' (CASD). Labour's obvious way out is to offer a free vote to its MPs - the least-bad option, in the circumstances - and to take the government's promise at face value. The policy review could concede that the Conservatives have the votes to secure Trident renewal, but require that the government do its due diligence. It could insist on a full accounting of where and how the money will be spent. It could ask for a detailed explanation of the need for CASD and its operational demands - including, for example, why the posture requires a fleet of four submarines, not the three that Gordon Brown suggested could be possible in 2009. It could outline the global strategic circumstances that would make possible an adjustment to CASD, or bolder steps in the future. It could propose British-led diplomatic initiatives and technical research to help get arms control and disarmament working again, a priority under the last Labour government. The review could, in short, compromise.

Jeremy Corbyn, vice-president of CND, must surely have spent much of his political life preparing for a fight over Trident. It would be understandable for him to think the moment for that fight has come. To save his party, he may have to think again.