Amber Rudd has sensationally quit the Cabinet and the Conservative Party in protest at Boris Johnson’s handling of Brexit.

The Hastings and Rye MP has quit her post as work and pensions secretary and said she was relinquishing the Tory whip after the Prime Minister sacked 21 rebels this week.

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Mr Johnson removed the whip from two former chancellors and Winston Churchill’s grandson after they voted to give Opposition MPs control of the order paper and start the process of blocking a no-deal Brexit.

Ms Rudd declared: “I cannot stand by as good, loyal moderate Conservatives are expelled.

“I have spoken to the PM and my Association Chairman to explain. I remain committed to the One Nation values that drew me into politics.”

In comments likely to reverberate across Westminster as it gears up for another tumultuous week, Ms Johnson said she thought a no-deal Brexit was now the Government’s main aim.

The former home secretary was dogged by questions throughout the Tory leadership contest about whether she could serve in Mr Johnson’s Cabinet if he won the race, given his strategy would involve keeping no-deal on the table during further negotiations with Brussels.

She accepted the offer of continuing in her job as work and pensions secretary when Mr Johnson formed his Cabinet in July.

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But in her letter of resignation, the now independent MP said that while she had accepted the need to keep no-deal as an option, she said she “no longer believed leaving with a deal is the Government’s main objective”.

Issuing forthright criticism of Mr Johnson, she called his decision to sack Tory rebels – such as ex-chancellor Philip Hammond, Churchill’s grandson Sir Nicholas Soames and Ken Clarke, the longest-serving MP in the commons – an “assault on decency and democracy”.

Ms Rudd, who was also minister for disabled people, added: “This short-sighted culling of my colleagues has stripped the party of broad-minded and dedicated Conservative MPs. I cannot support this act of political vandalism.

“Therefore, it is with regret that I am also surrendering the Conservative whip.”

Ms Rudd has represented her constituency since 2010 and has one of the smallest majorities in the country, with only 346 votes separating her from her Labour rival in 2017.

Conservatives called her decision to leave her post and party brave.

Health Secretary Matt Hancock tweeted: “So sorry to see Amber resign – a first-rate minister, genuinely wonderful person, and someone I’m proud to call my friend.”

David Gauke, ex-justice secretary and one of the Tories sacked this week, said: “Amber Rudd has been extraordinarily brave. But her concerns about how the Government is behaving reflect the views of many of my (former) colleagues.

“One way or another, it is time for them to act.”

Ian Lavery, Labour Party chairman, said Ms Rudd’s sudden resignation was a sign that “no-one trusts” the PM.

“The Prime Minister has run out of authority in record time and his Brexit plan has been exposed as a sham,” he said.

“No-one trusts Boris Johnson. Not his Cabinet, not his MPs, not even his own brother.”

SNP leader Westminster leader Ian Blackford called on the PM to resign following the walkout.

“Boris Johnson’s Tory government is on the verge of collapse – with no majority, no mandate and no right to pursue its reckless plans to impose an extreme Brexit,” said the Ross, Skye and Lochaber MP.

“The unelected Prime Minister must now do the decent thing and resign – he has no support or credibility left.”