Earlier this summer, a hundred or so Londoners gathered around a solar-powered stage truck at Highbury Fields to celebrate 40 years of Jeremy Corbyn in parliament. There was music, magic tricks and merriment. Attendees were encouraged to party like it was 2017. The opening act sang: ‘Jezza and me, we agree, we’re all for peace and justice and anti-austerity. We’re voting Jeremy Corbyn, JC for MP for me.’

For those in the Labour party watching from afar, this wasn’t just a celebration – it was the soft launch of Corbyn’s campaign to be the independent MP for Islington North. Just how many constituents will vote for him as an independent remains to be seen, but he can still inspire party-goers.

The villain of the day wasn’t Rishi Sunak, but Sir Keir Starmer. When Starmer was mentioned by a speaker – who described him as lying, self-interested and opportunistic – the audience booed and jeered. This dynamic represents a risk to Labour beyond the specific political ecosystem of north London. Left-wing voters, tired of Starmer’s move to the right, might in the next election vote Green, independent or not vote at all.

Corbyn, 74, has made little secret of the fact he wants to stay in politics. At an Edinburgh Fringe event this week (where he appeared alongside his old mate Red Len), he told the audience that he was ‘available to represent the people if that is what they wish’. He even refused to rule out running for London mayor: ‘Well let’s have a think about it, shall we?’

Few believe that Corbyn will really go so far as to try the Ken Livingstone route and join the mayoral race as an independent. While some of his old advisers have encouraged the idea, running for City Hall is expensive and requires nominations London-wide. Crowdfunding could be an option, however. The former Labour mayor for the North of Tyne, Jamie Driscoll, has raised more than £120,000 of his £150,000 target to fund his campaign to run as an independent.

If Corbyn did decide to run for London mayor, the fear in Labour isn’t that he would beat Sadiq Khan but that he would split the vote and let the Tories in. Changes brought in with the Electoral Reform Act 2022 mean that next year’s mayoral election will take place using first-past-the-post voting.

If Corbyn were to look for funds, some Tory donors would probably be more than happy to help. Polling for Redfield and Wilton taken in June suggested Corbyn would take a mere 7 per cent of the vote but this would cut Khan’s lead on the Conservatives to just 4 per cent. So it’s rather tight – particularly in the aftermath of the Tories’ narrow victory in the Uxbridge by-election. Starmer’s team have done little to hide their own frustration with Khan. ‘We should win the London mayoral race,’ says a Tory figure. ‘There are a lot of factors going in our favour – anti-Sadiq sentiment and Ulez.’

Should Corbyn stick to Islington North, Starmer allies are dismissive of the idea he could hold the Labour safe seat (majority: 26,188). But others in the party warn not to underestimate him. ‘It depends on the candidate,’ says one Labour figure. ‘If the party centrally imposes someone with no local connections and to the right, it’s possible he could do it. They need to pick someone on the left.’ Rumoured runners and riders include former Channel 4 hack Paul Mason – but the idea is yet to catch fire in Labour HQ.

Driscoll is another banished Labour politician refusing to go quietly. Blocked by the Labour leadership from standing for nomination as the candidate for North East mayor, he is going for it alone. Comments on his GoFundMe page complain about ‘the undemocratic and morally bankrupt excuse for a Labour leader’ and declare that ‘Labour is now a Tory tribute act’. Driscoll will ultimately be running against Labour – the candidate is Starmer-aligned Kim McGuinness, the favourite to take the new mayoralty.

He has cited the Livingstone model as evidence it is doable. Several Labour councillors quit in support along with the former media officer of Blyth Labour party who warned that a vote for the Labour candidate equals ‘a candidate that will agree to whatever her paymasters tell her, and her paymasters are the Labour London office’. As the public mood turns on Westminster, independents could have an electoral advantage.

These independents running against Labour touch upon a growing unhappiness at the direction of travel under Starmer. This week a shadow immigration minister confirmed that a Labour government would keep migrants on barges for a time, which led to more howls from the left (Corbyn accused Starmer of ‘political cowardice’). Policies that have seen mainstream Labour politicians like metro mayor Andy Burnham, and Scottish Labour leader Anas Sarwar clash with Starmer include the refusal to commit to free school meals and the insistence that the two-child benefit cap will remain. When Corbyn and Driscoll rail against these ‘climbdowns’ – including scaling back ambitions on climate – they are speaking to a part of the Labour coalition. The Green party, too, is defining itself against a ‘Tory-lite’ Starmer.

Labour’s electoral strategy is based on the idea that elections are won from the centre and wooing 2019 Tory swing voters is key. The belief is that these voters can be prioritised as liberal and left voters will vote tactically to get the Tories out. ‘The last two elections have seen extreme Labour vote share rises in the campaign on the back of green tactical voting,’ says one election analyst. But the last two elections also saw Labour led by a leader to the left of Starmer. Whether it’s from pragmatism or belief, Starmer is the most right-wing leader since Tony Blair.

This means he risks two problems. First, the difficulty of holding the line with his party once in power. Should Starmer have a small majority, the opinions of MPs on the left will become much more important. ‘They could hold the power,’ warns one Labour aide. Party elders are already suggesting Team Starmer ought to start befriending Lib Dems on the grounds that even with a majority their votes could be required. More immediately, Starmer needs to hope he doesn’t push Labour’s left-wing voters so far that they decide their interests are better served elsewhere. There’s no shortage of people keen for their votes.