Theresa May had started the day ­optimistically, suggesting to Today ­programme listeners that she could still win the vote on her Brexit deal, which would definitely go ahead next Tuesday.

With a little sleight of hand over the troublesome backstop she would persuade rebel Tory MPs that everything would be all right because they would “have a choice” about whether to use it.

Just 90 minutes after she came off air, however, the mask had slipped. ­Either side of 10am a succession of ­Cabinet ministers received phone calls from Downing Street calling them to an emergency meeting to discuss the Brexit deal vote.

Only when they received an email minutes later did they know who else would be attending – nine ministers in all, with Brexiteers outnumbered two to one by Remainers.

So unexpected was the summons that Philip Hammond, who had planned to spend most of the day debating the Brexit deal’s effect on the economy, had to leave the Commons chamber to head to Downing Street at 1.30pm.

Several ministers assumed they were about to be told about a new idea Mrs May had had to get her dying Brexit deal through Parliament.

Once inside her office, however, it became clear that she had invited them to a brainstorming session to discuss what, if anything, they could do to avoid a catastrophic defeat in the vote on Tuesday.