In what one colleague described as a highly emotional state, Maynard, who voted Leave, informed the PM in no uncertain terms that her Brexit strategy was doomed. She risked not only failing to deliver on the result of the referendum, but also destroying the Conservative party, Maynard said, according to two sources in the room.

“I think things are slipping away from us,” he went on, explaining his verdict that they would not be able to find the numbers for her deal to pass unless she made a public commitment to stand down. The pledge to quit should be made in the Sunday newspapers ahead of the vote on her deal, Maynard said.

May sat motionless for a few seconds, “taken aback”, according to a source, then replied: “Thank you for your honesty”, before moving the conversation on. But in the course of the next 15 minutes, her other whips offered similar assessments of the situation.

One by one they told her that her deal would never get through unless Tory MPs received guarantees about the future leadership of the party. The message was clear from the custodians of her government: She had to go. “It was like the Murder on the Orient Express,” a source said.

Yet May was unmoved, expressing her belief that her departure would not make any difference to the success of her deal. The despairing whips left the meeting convinced that she would not do the one thing they believed would help persuade Brexiteer rebels to switch.

The extraordinary showdown occurred, BuzzFeed News can reveal, as cabinet ministers openly plot this weekend to oust May as prime minister.

In phone calls and meetings over the last two days, several of May’s most senior ministers discussed jointly telling her she has to resign if she cannot get her Brexit deal through the Commons next week. One cabinet minister told colleagues the PM has “days” left in Number 10.

The ministers said they cannot stay in the government if either a long extension to Article 50 or a softer Brexit becomes UK policy over the next two weeks, and indicated they would seek to bring May down if such a scenario became reality.

These ministers are said to include Remain voters who now back Brexit including Gavin Williamson, Jeremy Hunt, Liz Truss, and Sajid Javid, as well as Leave voters including Andrea Leadsom. “Theresa would be facing a large-scale walkout the likes of which have never been seen before,” a source familiar with the discussions between the ministers said.

As May faces explicit threats to her premiership from either side of her bitterly divided cabinet, other ministers led by Amber Rudd, Greg Clark, and David Gauke demanded free votes on alternative plans for a softer Brexit next week. They are also prepared to attempt to end May’s premiership if she takes the country towards a no-deal Brexit.