As the press gathered in Downing Street for an early evening press conference, the Prime Minister stuck to her plan and refused to budge on her widely panned Brexit deal.

Theresa May’s day began with the shadow Brexit secretary telling morning news shows that Labour would be voting down her deal. Probably not a shock, but the start of a day she might want to forget.

In Brussels the EU’s chief negotiator Michel Barnier and the president of the European Council Donald Tusk started their day announcing an EU summit to formalise the UK’s withdrawal agreement on November 25. Despite celebrating the deal, Tusk called Brexit a “lose-lose situation” and that the agreement was all about damage limitation.

At the same time, back in Westminster the first resignation of the prime minister’s government was announced. Shailesh Vara, a minister for Northern Ireland said the UK “can do better” than the PM’s “half-way house” deal.

Vara’s announcement was rather overshadowed, however, as shortly before 9am Dominic Raab, the Brexit secretary, announced his resignation from the Cabinet. Raab said May’s deal agreed for Britain to be bound by the EU, “imposed externally without any democratic control”. He also cited the promises the Conservatives made in their 2017 manifesto. “This is, at its heart, a matter of public trust,” he wrote in his resignation letter.

Gina Miller, the businesswoman who fought the government at the Supreme Court over granting parliament a vote over this final deal, likened Raab’s resignation to “marking your own homework and failing it”.

Another five resignations followed, including the work and pensions secretary Esther McVey, Suella Braverman, a junior minister in the Brexit department and the Tory party vice-chair Rehman Chishti.

Mrs May then departed Downing Street for parliament, where she faced three hours of criticism from all sides of the Commons. The most crushing comments coming from her own benches. The chairman of the European Research Group,  Jacob Rees-Mogg picked apart the deal against previous promises made by the prime minister. He asked her directly whether he should write to Graham Brady, the chair of the 1922 Committee, and submit a letter of no-confidence in her.

Addressing the PM and the House, he said: “My Right Honourable Friend, and she is unquestionably honourable, said we would leave the customs union. Annex 2 says otherwise.

“My Right Honourable Friend said that she would maintain the integrity of the UK. A whole protocol says otherwise.

“My Right Honourable Friend said that we would be out of the jurisdiction of the European Court of Justice. Article 174 says otherwise.

“As what my Right Honourable Friend says and what my Right Honourable Friend does no longer match, should I not write to [Graham Brady]?”

Moments after leaving the chamber, Rees-Mogg confirmed his intention to send a letter of no-confidence, as he addressed the media outside parliament.

After this most bruising of days, when Downing Street announced Mrs May was to hold a press conference at 5pm, many thought she could be about to announce her resignation. However, she did quite the opposite and instead doubled down on her Brexit plans. “I believe with every fibre of my being,” she said, “that the course I have set out is the right one for our country and all our people.”

She told reporters that she was going nowhere, using a cricket analogy: “Geoffrey Boycott stuck at it, and he got the runs in the end.”

Reacting to speculation that Michael Gove had been offered the job of Brexit secretary, she praised Gove’s work as environment secretary but said she hadn’t yet appointed a replacement for Dominic Raab: “I will be making new appointments in due course.”

The prime minister’s strategy of digging her heels in and getting on with her plan has saved her premiership numerous times before. None, however, quite of this magnitude. The question on almost everybody’s lips tonight: Are her days in Downing Street coming to a rapid end?

As a result of the turmoil in Westminster, the pound had an uncertain day. After the Brexit secretary stepped down at 9am, sterling tanked. This paved the way for a damaging day in the City.

Even if Theresa May survives a vote on her leadership, she still has what looks like an impossible task of getting her deal through parliament. A vote on the withdrawal agreement is likely to take place in December.