What will happen to Brexit after John Bercow’s dramatic intervention?

The Commons speaker stunned the government yesterday by announcing that Ms May cannot hold another vote on her Brexit deal – not, that is, unless it has changed significantly.

Downing Street had no idea the dramatic statement was coming. It blew out of the water its strategy of holding another vote on the deal this week, before Ms May heads to an EU summit on Thursday, and probably another next week.

The government may have one more shot at getting its deal through, but Mr Bercow warned ministers that for another vote to go ahead, the agreement must have changed “substantially”.

That is not impossible. Ms May will request, and probably be granted, a delay to Brexit at the European Council meeting this week. Ministers are likely to claim that this marks a clear change of circumstances and that another vote should therefore be allowed.

But in a worrying sign for No 10, Mr Bercow suggested that for another vote to take place, the deal itself would have to have been altered, not just the circumstances around it.

The government could, in theory, find a procedural way around this. The rule invoked by Mr Bercow says a vote cannot be held on the same matter in the same parliamentary session. The current session is due to end in May, meaning No 10 would be fully entitled to call another “meaningful vote” immediately after this. It could even bring the end of the parliamentary year forward – a move mooted yesterday by Robert Buckland, the solicitor general.

Ministers could also hold a Commons vote on disapplying the rule that stops multiple votes being held, though asking parliament to override centuries of convention would be highly controversial.

The reality, though, is that regardless of Mr Bercow’s intervention, it was far from certain that Ms May’s deal would have been approved by MPs voting on it for the third, fourth or even fifth time. If they stuck to their guns, the rump of around 20-30 hardline Tory opponents were numerous enough to defeat it again and again.

That, along with the speaker’s ruling, may force the prime minister to go back to the drawing board. She will do everything possible to avoid doing so, having spent almost her entire time in office working on the deal she agreed with the EU.

She has few options left. She could try to negotiate a totally different Brexit deal, call a general election or hold another referendum, but any of these choices are likely to result in her departure from office. Scrapping her deal would be an astonishing admission of failure, Tory MPs will not allow her to fight another general election, and she has repeatedly said a fresh referendum will not take place while she is prime minister.

In typical fashion, it appears the prime minister is indeed sticking with plan A.

Stephen Barclay, the Brexit secretary, suggested on Tuesday that MPs switching their support and the EU agreeing to delay Brexit would be enough of a change to justify a third vote, telling the BBC: “If we see a number of members of parliament changing their vote, if we see clarity in terms of an extension from the council, then these are the issues on which members of parliament, I’m sure, will find a way through.”

It seems unlikely that Mr Bercow will agree. He has made his position very clear, and is, to put it mildly, a man not afraid to cause a stir.

The prime minister will then face a choice: does she force a vote to overrule the 1604 convention that the speaker is relying on, or does she admit her deal is dead?

Ms May will desperately try to find a way to hold another vote, but her escape routes are closing by the day. Mr Bercow’s explosive intervention has made her situation even trickier but it does not change the fundamental question: how, if at all, can the prime minister secure MPs’ backing for a deal they have twice rejected? It is a question that No 10 still seems unable to answer.