Jeremy Corbyn’s plan to become caretaker Prime Minister in a government of national unity is a tremendous wheeze. I

wonder who thought of it?

It has many attractions, chiefly the ousting of Alexander de Pfeffel Johnson, aka Bonking Boris, from Downing Street.

The main drawback is that, however well-intentioned, it isn’t going to happen.

To succeed, the plot requires the support of rival Opposition parties.

The Lib Dems, scenting power for the first time since joining the Cameron coalition, have rejected it out of hand.

It needs the backing of rebel Tory MPs, but with the Conservatives edging into the lead in the latest opinion poll, why should they rally to a politician they openly despise?

Change UK nobodies say “No”, and SNP co-operation would be conditional on another independence referendum, which is too high a price.

The plan is also stacked like falling dominoes. First, a successful vote of no-confidence in Johnson and a

parliamentary block on a no-deal Brexit.

Then the Queen sending for Corbyn to form a “time-limited” government.

Followed by an election, in which Labour campaigns for a second referendum with Remain on the ballot paper.

And wins.

If one domino stays upright, it all goes down the pan.

Which is a shame, because the same poll putting the Tories ahead also shows support for Remain now running at 55%, with Leave on 45% – a reversal of the 2016 result.

The real problem is that Corbyn’s wheeze has come too late.

Years of dithering – which almost cost Labour its deposit

in the recent Brecon by-election – have taken their toll on our credibility.

Possibly, fatally.

I say “our” because I’m still a party member, loyal for 33 years, and unlike Alastair Campbell, I’ll vote Labour whoever is the leader and whatever happens to Brexit.

But I fear we are in for another long haul, like the locust years of the 80s and 90s, and no certainty at the end of it.