Three government ministers have resigned in order to vote for giving Parliament control over the Brexit process - removing power from the prime minister.
Richard Harrington, Alistair Burt and Steve Brine quit the government to vote for the so-called Letwin amendment, a plan that aims to give MPs a series of "indicative votes" on alternatives to the Prime Minister’s deal.
Their departure means a total of 22 ministers have quit during the past 12 months, including five members of the Cabinet - and more are expected.
Richard Harrington, resigned as business minister
Richard Harrington, MP for Watford who was first elected in 2010, had been a fervent supporter of the prime minister on social media, despite making threats to defy government orders over exiting the EU.
His loyalty to Theresa May held out until Monday evening, when he resigned as business minister, accusing the Government of "playing roulette" with the lives and livelihoods of the people of Britain in its handling of Brexit.
He voted against the direction of his boss to give MPs control over the Commons agenda, telling ITV News "the time has now come" to stop the PM's deal or no deal being the only options.
When asked about alternatives, he said: "I'd look for any way that can accept what people voted for, which was to leave the European Union but not cause irrevokable damage to people's jobs and lives, which I believe no deal would do."
He added: "The prime minister decided to go for, I call it, the Tory-only solution, which is to try and reconcile very different views within the Conservative Party and that, just from the arithmetic, clearly was not possible.
"Now, I feel it's our last chance to get together, I hope in a non-political party way."
In his letter of resignation, Mr Harrington made a scathing assessment of the Government's Brexit negotiations so far.
The former business minister said: "The failure to secure a deal and to rule out a hard Brexit is resulting in cancelled investment decisions, business being placed abroad, and a sense of ridicule for British business, across the world."
Alistair Burt, resigned as Foreign Office minister
North East Bedfordshire MP Alistair Burt also defied Mrs May by resigning to vote for the Letwin amendment.
The Parliament veteran, who was first elected in 1983 before losing his seat in 1997 and regaining it in 2001, has previously made clear his unwillingness to accept a no-deal departure.
It appears to have been that resolve which led him to hand in his resignation letter, saying he did so "for the country's sake".
In the letter, he said: "Despite the best and determined efforts of the Prime Minister, her agreement with the EU continues to be rejected by Parliament.
"We are running out of time for an alternative, and the risk of leaving without a deal, and continuing serious and disruptive uncertainty is affecting the UK profoundly."
He added: "Parliament should seek urgently to resolve the situation by considering alternatives freely, without the instruction of party whips, and Government should adopt any feasible outcome as its own in order to progress matters.
"I did not believe the Government was prepared to do that, so had to vote to ensure this happens."
Steve Brine, resigned as health minister
Steve Brine, MP for Winchester & Chandler's Ford, suggested the revolt in favour of the indicative votes amendment could actually boost the chances of Mrs May's deal finally getting through.
The MP, who was first elected in 2010, said in his resignation letter the reason for his departure was over his belief in the need for exiting the EU with a deal.
He reiterated that to ITV News, saying: "I think that the House of Commons has said for a long time that it doesn't want to leave without a withdrawal agreement and I agree".
He said he hoped MPs could support the PMs deal, but if not "we need a plan B and that's what this was about, it's about Parliament helping out the executive".
He added: "There comes a point where you've got to make a stand and you've got to make that happen."
In his resignation letter, he said: "I feel so passionate that leaving without a withdrawal agreement (commonly referred to as a ‘deal’) is not acceptable to me or in the national interest."
He told the prime minister he supported her deal but said the only way to achieve it would be to give MPs a "series of ‘indicative’ votes" by backing the Letwin amendment.
He added: "At this stage in the endgame of the Brexit process, I was not prepared to vote against that (or another amendment which again makes clear our wish to avoid no deal) so the honourable thing was to leave the Government tonight and vote accordingly."