Scottish Labour's decision to vote against Trident renewal means that the party faces not just a left-right split but a north-south one too. The UK party continues to officially support renewal after voting not to debate the issue at its annual conference in September. But Scottish Labour delegates today voted by 70-30 per cent to scrap Trident. Nicola Sturgeon immediately highlighted the division, tweeting: "Good news that @scottishlabour has voted against Trident renewal...but it will only make a difference if UK Lab MPs vote against it in HoC." Should the UK party continue to back renewal, the SNP will argue that it merely proves the need for independence.

The Scottish party's decision is a defeat for leader Kezia Dugdale, who supports multilateral disarmament, and a victory for shadow Scottish secretary Ian Murray (and Labour's only MP north of the border) who opposes renewal. As a lifelong unilateralist, Jeremy Corbyn had encouraged delegates to reject Trident. The CND vice-president said in his speech to the conference on Friday: "[Keir] Hardie’s 'sunshine of socialism' was about providing people with decent housing, it was about promoting peace and defending jobs – and there is no contradiction between those last two points. We know there are skilled jobs in the defence industry. We cannot be negligent about skills and jobs. We must secure every one of them. But don’t tell me we can’t put those skills to better use: the innovators, the engineers, the technicians, the security staff and the civil servants too. No one should even consider allocating a penny saved on not renewing Trident until those skills and jobs are protected through a proper programme of diversification."

Maria Eagle, the shadow defence secretary, who supports renewal, is currently leading a review for the UK party. She told me last month that it would examine Trident "with a completely open mind" and said she was "not ruling out" endorsing unilateralism. Eagle's review is not due to be completed until the new year but Labour is likely to soon be forced to take a position. The SNP will almost certainly use its opposition day on 24 November to debate the issue and the Conservatives are considering bringing forward the vote on "maingate" renewal to December.

Only a handful of shadow cabinet members (Diane Abbott, John McDonnell, Jon Trickett, Murray) share Corbyn's unilateralism, with a majority, including Eagle, opposed. Andy Burnham has said he would resign if the party rejected renewal and others would llikely follow. Most expect Corbyn to allow shadow cabinet members a free vote but this would allow both the Tories and the SNP to denounce Labour as "weak" and "divided". One shadow cabinet member quipped that it would be "The first time a leader had called a free vote to allow himself to vote against party policy". Unless the UK Labour conference and National Policy Forum vote against renewal the party's official stance will remain one of support. The Scottish section's decision has made an already fraught divide worse.

Update: Unsurprisingly, Jeremy Corbyn has welcomed the result. A spokesperson said: "The vote by the Scottish Labour Party Conference on Trident renewal and the protection of defence jobs is a clear sign that Labour's democracy has opened up. Scottish Labour Party members have spoken. That will now feed into the wider UK Labour debate and review of defence policy."