Since the election date for next year’s London mayoral election was announced, Sadiq Khan has been putting on a show of confidence that his re-election is in the bag with his supporters pointing to polling that suggests Labour enjoy a 40-point lead in the capital. However, the Ulez expansion – which Keir Starmer blamed on his failure to take Uxbridge in last month’s by-election – has certainly put a spring in the step of his Tory mayoral opponent Susan Hall.

Now could a fresh nightmare be heading his way? It appears the incumbent Mayor of London might have an unwelcome challenger at next year’s election in the shape of none other than former Labour leader Jeremy Corbyn. Speaking on a panel at the Edinburgh Fringe this weekend, Corbyn gave an enigmatic hint that he might put himself forward as a candidate for Mayor.

Asked if he would consider throwing his hat into the ring, Corbyn replied: ‘Well let’s have a think about it, shall we?’ With words that might well make Khan quake, he continued, ‘I want to see change in our society. I’m not disappearing, I’m not going away. I look at my diary and I’m more active than I have ever been at any other time in my life.’ Now that sounds like a challenge.

Corbyn, currently sitting as an independent MP for Islington North, was thrown out of the Labour party earlier this year after refusing to apologise for the antisemitism row that engulfed it. His expulsion divided the party membership, and Corbyn still commands considerable support within the local Labour party and constituency – with many unhappy that he is being blocked from standing as a Labour candidate at the next election.

Could Corbyn now take his independent approach London-wide to the mayoral contest? This is a scenario that has long worried Labour figures. Such a move could see the Labour vote split – thereby helping the Tories even if Corbyn himself is likely to fall short. It’s why the hope in Labour circles is that Corbyn will fail to find the funds to embark on such a campaign.