Denis MacShane was a TUC delegate in the 1970s, an international union official in the 1980s, and chaired the Steel group of MPs in the Commons.

With the GMB’s call for a public vote on the final Brexit deal, the campaign to get the Labour party to follow suit moves into a different gear. The GMB is the UK’s second largest private sector union, has 640,000 members and sponsors 80 Labour MPs.

GMB MPs are strong outside of the M25 and include Jo Stevens, the Cardiff MP, and Ruth Smeeth, in Stoke-on-Trent. Another key GMB MP is Dawn Butler, the Labour’s shadow women and equalities minister. The union traditionally organises along the M62 chemical plants corridor.

The GMB’s 80 Labour MPs join the 20 Labour MPs sponsored by the steel and textile workers’ union, Community, which backed a People’s Vote last month. That includes Caroline Flint who chairs the union’s group in the Commons.

The third Labour-affiliated union to have come out for a new vote is the TSSA, the transport workers union, with eight Labour MPs including John Cryer, the chair of the Parliamentary Labour Party. Cat Smith, MP for Lancaster and Fleetwood, and Rachael Maskell, the York MP are well-liked and hard-working TSSA-sponsored MPs covering the North West and Yorkshire.

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Another TSSA-sponsored MP is the high-profile Clive Lewis, who resigned from the shadow cabinet as defence spokesperson to vote against triggering Article 50 in February 2017. He was joined by 51 other Labour MPs who opposed the official Labour party line of voting with Theresa May.

Now, as more and more employees worry about their future of the jobs, especially in exporting industries like chemicals which rely on just-in-time deliveries to and from the EU, the idea that Brexit can be anything other than a disaster for jobs and investment is gaining hold.

This has been a constant theme at union conferences this summer and will be reflected at the TUC’s annual congress in Manchester next week. The UK’s biggest union is Unison. At its June conference delegates from every sector of the UK public services – hospitals to local authorities, as well as universities – condemned Brexit. Unison has 75,000 EU citizens among its membership. Fears over the chaotic lack of clarity around the precise details of their status and right to have families living with them in post-Brexit Britain is strong.

So that’s just over 100 Labour MPs now in unions calling for a public vote on Brexit – approaching half the Labour members in Parliament. To be sure, Labour MPs do not have to follow union orders, but unions represent working-class voters in the Labour heartland and cannot be ignored.

In the 1930s when Labour organised petitions against fascism but refused to support rearmament and intervention in Spain, it was the trade unions that forced Labour to come back to their senses. Similarly in the 1980s when Labour adopted a Brexit policy in its 1983 manifesto, it was unions that worked inside Labour to win support for staying in Europe.

Once again the trade unions may save Labour, from two years of refusing to oppose Brexit and trailing behind the Tories, by allowing the people a voice.

Edited by Luke Lythgoe