Boris Johnson lost his first vote in parliament, so prepare for a general election in just five weeks

Monday is the last day the house can sit if a nationwide ballot is to be called on the government's new proposed date of 15 October

Boris Johnson, like Pitt the Younger in 1783, lost his first vote as prime minister in the House of Commons. And he lost it by a larger margin – 27 votes – than anyone had expected.

There may be further twists and turns in the plot to come, but tonight it looks likely that Hilary Benn’s bill to block a no-deal Brexit will be passed by the Commons on Wednesday evening. There are certainly enough “rebel alliance” votes to pass it – the only question is whether there are other devices the government can deploy to stop it. If it is passed, it will complete all its Commons stages in a few hours, and will then go to the House of Lords, which is also likely to pass it, although how long that will take no one knows.

In a defiant response to tonight’s vote, Johnson said that, although he doesn’t want a general election, “if this bill is passed tomorrow, the public will have to choose who goes to Brussels on 17 October”.

That means he will ask MPs to vote for an election, probably on 15 October, by the two-thirds majority required by the Fixed-term Parliaments Act. That vote is expected to take place on Wednesday evening, as soon as the Benn bill passes the Commons.

But there is a problem.

After a day of confusion about Labour’s position, Jeremy Corbyn responded to Johnson’s demand for an election by saying the Benn bill had to become law first. “Fine,” Corbyn said. “Get the bill through first in order to take no deal off the table.”

So it may be that the vote to hold an early election won’t be held until Monday, to give the House of Lords time to complete the passage of the bill. I understand that Monday is the last day that parliament can sit if the election is to be held on 15 October. The government’s original plan was for the election to be on 14 October, but that would have required parliament to be dissolved before Monday, as the law requires one day for dissolution and 25 working days for the election period. (Also, 14 October is a Jewish holiday, on which some observant Jews are forbidden to work, which includes voting).

What is interesting is that Corbyn seems happy to go along with an election as long as it is held before Brexit day, so that an incoming Labour government could presumably ask for an extension to the deadline in order to negotiate a better deal.

This will upset a lot of Remainer Labour MPs, who were hoping to force Johnson to secure the extension and then to hold an election after that. They fear that either Corbyn will lose the election – which would give Johnson a mandate for a no-deal Brexit – or that he will win it and still try to take Britain out of the EU, although that would, under Labour’s new policy, now be subject to a further referendum.

As it is, prepare for an election in five weeks’ time.