Speaker Bercow has ruled that the government cannot bring its Brexit deal back to the Commons for a third meaningful vote unless the deal is substantially different.

Making an unplanned announcement this afternoon, Bercow said: “If the government wishes to bring forward a new proposition that is neither the same nor substantially the same as that disposed of by the House on 12th March, this would be entirely in order.”

He went on to confirm that the government “cannot legitimately” put forward “the same proposition” to the Commons, citing Erskine May – the parliamentary rulebook that forms part of the UK’s uncodified constitution – in his explanation.

“A motion or an amendment which is the same, in substance, as a question which has been decided during a session may not be brought forward again during that same session,” Erskine May reads. “Whether the second motion is substantively the same as the first is a matter for the chair.”

Following the defeat of Theresa May’s deal at the second meaningful vote, it was widely expected that she would bring it back to a third – ‘MV3’ – on Tuesday or Wednesday this week. But Downing Street said earlier today that it would only be put to another vote once talks with the DUP had concluded (and, presumably, progress had been made).

Asked by Labour backbencher Hilary Benn whether changes to the deal would have to entail an agreement with the EU, or whether a new agreement with another political party would suffice, Bercow suggested in response that a shift of opinion “wouldn’t itself constitute change of the offer”.

The plan, according to No10 and to the Article 50 extension passed by MPs last week, was for May to ask the EU for a long delay to Brexit unless her deal was passed before 20th March. As it seems unlikely that the Prime Minister will be able to secure substantial changes to her deal before the EU summit later in the week, it is highly probable that such a request will be made.