Peter Kellner is former president of YouGov.

Two years ago, Wales voted to Leave the EU by 53% to 47%. Scotland and Northern Ireland voted Remain. The latest YouGov research suggests that Wales may have changed sides. If a referendum were held now, it may well produce Remain majorities in all three nations of the United Kingdom outside England. With London firmly in the pro-EU camp, a new referendum could turn into a tussle between provincial England and the rest of the UK.

The majority in Wales for staying in the EU is still narrow: it commands 51% support, while Leave has 49%. However, as with all of YouGov’s polls, it is able to compare how people say they would vote now with what the same people told YouGov at the time of the 2016 referendum about their vote then. In short, while the scale of the shift to staying in the EU is subject to a margin of error, the fact of a shift is beyond doubt.

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The shift has been driven by Labour voters, where the swing is 6%, double the average for all Welsh voters. In the referendum two years ago, Labour supporters voted 66% to 34% for Remain. This has now widened to 72% versus 28%. Labour voters also back a People’s Vote by almost three-to-one: 61% to 22%. These numbers should concern those Labour MPs who are resisting both continued membership of the EU and a fresh referendum to let the people decide the issue.

While the shift to staying in the EU will vary from seat to seat, the figures suggest that a number of Labour MPs who represent Leave constituencies would be likely to find that a referendum today would show that their local voters have switched sides.

In 2016, 22 of the seats currently held by Labour voted Leave; just six voted Remain. A referendum today could produce up to eight seats moving to support staying in the EU. Five seats that look likely to change sides are Ynys Mons, Delyn, Newport West, Neath and Gower. Three more that could go either way are Caerphilly, Llanelli and the Vale of Clwyd. If all eight switched sides, the balance of Labour seats in Wales would go from 22-6 in favour of leave to 14-14.

It’s something to think about for the Labour leadership. The news of a shift in Wales coincides with key union figures such as the GMB’s Tim Roache and TUC boss Frances O’Grady calling this week for a public decision on Brexit. Pressure will be high at the Labour Party Conference at the end of the month for Jeremy Corbyn to back the people getting a proper say on Brexit.

Edited by Luke Lythgoe