My first assessment of Labour’s chances in Stoke-on-Trent was fairly upbeat: I thought that Labour would likely hold the seat and that if there was a threat, it would come not from Ukip but from the Conservatives.

Now Ukip’s leader, Paul Nuttall, has been announced as the candidate for that party. Does that change things?

A lot has been written about how Nuttall, who is from Merseyside, presents an existential threat to Labour “up North”. Stoke is an imperfect test of that for many reasons, not least because it is in the West Midlands, but it’s worth noting that so far, “the Nuttall effect” has been conspicuous by its absence.

It hasn’t helped arrest Ukip’s collapse in local council by-elections. It didn’t prevent the Ukip vote declining in Sleaford and North Hykeham, a by-election, like Stoke-on-Trent, where the Leave vote outperformed the national average.

What has happened is that people who voted Labour in 2010 but Ukip in 2015 are still putting their cross in the Ukip box, but people who voted Conservative in 2010 but Ukip in 2015 have been drawn back to the Conservative fold. To add to Labour’s misery, since the referendum, there has been some slippage among Labour voters to the Liberal Democrats.

So all other things being equal, if there is a threat to Labour in Stoke it comes from the Tories, not Ukip. But in a boost to Labour, both parties finished on 22 per cent of the vote, with just 33 votes separating Ukip in second from the Tories in third. That makes it harder for either party to say “vote x to beat Labour”.

My feeling – which seems to be the majority view on the ground in Stoke – that if there is a threat it comes from the Tories coming through the middle, rather than Ukip directly. If the story of the by-election is a knife fight between Labour and Ukip, yes, that helps Ukip squeeze the Tory vote. But it also makes it less likely that anyone who might have switched from Labour to the Liberal Democrats as a result of the referendum – and they had a good second place in 2010 – will do so, making Labour’s position more secure.

Of course, I could be wrong. It could be that Nigel Farage’s outsized media profile means that most voters – who understandably don’t follow the ins and outs of the third party – still think he is the leader, and that my estimation of Paul Nuttall’s electoral pull is wildly off-beam.

And it’s worth noting that the Labour leadership are jittery about the seat. They are keen to have the by-election quickly to prevent their opponents getting a good run-up and put pressure on Tristram Hunt, once he had announced his resignation, to quit quickly and allow them to start the campaign period as soon as possible.

But my strong hunch remains: if there is a threat to Labour in Stoke it is from the Conservatives, and anything which distracts from that is good news for Jeremy Corbyn’s hopes of holding the seat.