Just five years ago, London was a key political battleground and County Durham was a Labour heartland. But since Boris Johnson swapped City Hall for Downing Street, those situations appear to have reversed, with the capital a key base for the party. Labour’s voters in London, however, could soon be leaving. And its hopes for long-term electoral gains hinge not just on winning back seats lost to the Conservatives in northern England, where the party is likely to suffer even further in Thursday’s elections, but on appealing to new, younger voters in the south priced out of popular cities. Starmer’s office will be closely watching a number of southern races for signs of green shoots which, if absent, might indicate that Labour has a bigger problem – that it is failing to capitalise in areas where demographics are moving in its favour. One key race is the West of England mayoralty, where there are hopes that former Labour MP Dan Norris can take the seat off the Tories, whose incumbent is retiring. If they do, it will be a promising sign that the strong Labour vote in Bristol, a fairly recent resurgence, is growing still – as well as in its commuter towns. “This is the race that is going to show that Labour have a chance of making this kind of shift happen,” said Chris Curtis, senior research manager at Opinium. Labour will hope to regain its majority in Crawley after two councillors quit to put the West Sussex council into no overall control. Control of the jointly managed Adur and Worthing councils on the south coast is also in the balance and even modest Labour gains would be promising as part of a long-term south coast strategy. Key targets are East Worthing, Shoreham and Worthing West. Even places where Labour will not win overall are being watched for signs they could be part of a national election strategy. One contest mentioned by Labour aides is the Devon and Cornwall police and crime commissioner race, where the party is hoping to see evidence it is gaining voters in that area. London is now viewed by the Conservatives as essentially as a lost cause to Sadiq Khan’s people’s republic, an attitude that has irritated Tories in the capital who point out their party still managed decent results in the 2018 elections. If Khan’s dominance starts a trend, there are at least eight seats in London alone that Labour should hope to gain at the next election – including Johnson’s seat in Uxbridge. “There are short memories here,” one Tory MP said. “The dominance of Labour in London is not historic. The Tories literally held Brighton Kemptown until 2017. We have to keep an eye on the seats Blair managed to win – and the seats where he came close and where the demographics have kept on changing favourably for Labour. So seats in Hertfordshire like Welwyn and Stevenage.” There are already concrete signs of a shift in the south, which Labour knows it must exploit. Portsmouth South, where Labour finished third even in 1997, it has now won twice, a change that has little to do with converting Conservatives and far more to do with the opening of a university campus. One Labour adviser said: “Over the last two years, lots and lots of people have moved out of London. That will have been accelerated by Covid. We read a lot about the red wall. No one has gone to Wycombe to find out what is driving down Steve Baker’s majority.” Labour’s advance in national polls, which has recently been draining away, has never been at the expense of the Conservatives, instead coming almost exclusively from poaching the Liberal Democrat vote. In some areas, like St Albans, which the Lib Dems won in 2019, this could benefit the Conservatives. In others, it could start to see Labour challenge for seats in Somerset, Hampshire and Cornwall. “The south-west has voters in quite a progressive, even radical tradition. They used to go Lib Dem,” one Tory MP observed. “Now they don’t really have anyone to vote for. A Labour party who wants to win nationally has to take those votes. They have to run Jacob Rees-Mogg [in North East Somerset] close.” None of this is a replacement for winning back northern English seats, but would have to be done in addition to that, as well as making significant gains from the SNP in Scotland. Overall, Labour aides are braced for a punishing night in Thursday’s local and devolved elections, even beyond the totemic Hartlepool byelection where the media narrative has been focused. Key councils like Bolton and Durham are likely to move from Labour to having no overall control. Labour will say that many of the most difficult results will come in councils like Sunderland where there have been no elections since 2016, an electoral lifetime ago in terms of political events, meaning the seats there have yet to shift definitively along with the national picture. Curtis said Labour should not automatically view that result as an indication things are getting worse for the party: “There has been a significant realignment since those places last voted and many will just be catching up on that realignment. “The next Labour party that wins a national election is not going to win back all of the red wall, it is not going to win back all of Scotland, or all the southern seats it could win, it will do a little bit of everything, and it will probably involve seats like Bournemouth and High Wycombe.” • This article was amended on 5 May 2021 to correct the name of Jacob Rees-Mogg’s constituency from “North West Somerset”.