IT began when two of the most senior members of his Government quit – but it took three days and 59 letters of resignations for the Prime Minister to finally admit defeat.

In his resignation speech, Boris Johnson blamed the “herd instinct” of Tory MPs for pushing him out of office after an extraordinary 72-hour stand-off between the Prime Minister and members of his Cabinet.

Speaking outside Downing Street on Thursday, Mr Johnson acknowledged that “no one is remotely indispensable” and accepted that it was the “will of the parliamentary Conservative Party” that he should leave No 10.

The nail in the coffin for the Prime Minister came in the form of former Tory deputy chief whip Chris Pincher, who resigned from his government job amid allegations he groped two men at a private members’ club.

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It emerged that Johnson had been told about previous concerns about the MP’s behaviour as far back as 2019 but decided to promote him anyway.

Downing Street claimed that Mr Johnson forgot he had been told about the claims and the Prime Minister was forced into a grovelling apology.

It was too late. Within minutes, his Government was thrown into disarray when Sajid Javid resigned as health secretary over the scandal.

Almost instantaneously, Chancellor Rishi Sunak also confirmed he was also quitting.

By Wednesday morning, dozens of ministers and MPs with government briefs had lined up to resign and vent their anger at the Prime Minister.

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But this time, there was a growing sense of personal frustration from many of Mr Johnson’s party allies.

Children’s Minister Will Quince defended Mr Johnson during a media round on Monday, insisting he had asked Downing Street “firmly and clear” what had happened.

But when it emerged Mr Johnson had prior knowledge of allegations, Mr Quince said he had “no choice” but to resign having been given “accepted and repeated assurances”.

At PMQs, 1922 Committee Executive Secretary Gary Sambrook angrily told MPs that in an “attempt to boost morale in the tea room”, the Prime Minister said that “there were seven people, MPs, in the Carlton Club ... last week and one of them should have tried to intervene to stop Chris from drinking so much”.

Mr Sambrook added: “As if that wasn’t insulting enough to the people who did try and intervene that night. And then also to the victims that drink was the problem.”

“Isn’t it the example that the Prime Minister constantly tries to deflect from the issue, always tries to blame other people for mistakes and that leaves at least nothing left for him to do other than to take responsibility and resign?”

In his no confidence letter, Chris Skidmore claimed the situation was “tantamount to an effective cover-up of sexual abuse that would never be tolerated in any normal, functioning, workplace.”

By Wednesday night, a delegation of ministers including Transport Secretary Grant Shapps, Home Secretary Priti Patel and Northern Ireland Secretary Brandon Lewis pleaded with the Prime Minister to make a “dignified” exit.

The Herald: Home Secretary Priti PatelHome Secretary Priti Patel

Instead, Mr Johnson furiously sacked Cabinet rival Michael Gove over the phone after the then Levelling Up Secretary lent his voice to the chorus telling Mr Johnston that he had lost the confidence of the party.

The resignations kept coming, with the revolt against Mr Johnson growing to include his new chancellor, Nadhim Zahawi, who had been in post for two days. Education Secretary Michelle Donelan also tendered her resignation after less than 36 hours in her new post. 

And so, early on Thursday morning, Mr Johnson rang Graham Brady, Chair of the influential 1922 Committee, to concede that he had lost the support of his party.

The stage outside Downing Street was set and, by lunchtime, Mr Johnson emerged from No 10 to concede his premiership.

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It was not a traditional concession speech, however, as Mr Johnson described his colleagues’ decision to oust him as “eccentric”, hinting they had been driven by a “herd” mentality.

“In the last few days I have tried to persuade my colleagues that it would be eccentric to change governments when we are delivering so much and when we have such a vast mandate and when we are actually only a handful of points behind in the polls,” he said.

“As we’ve seen at Westminster, the herd is powerful and when the herd moves, it moves.”

The defeated Prime Minister made no apology for any of the self-inflicted scandals that prompted his party to turn against him, instead highlighting the “incredible mandate” that his party had won in the 2019 General Election and his successes in office, such as the vaccine rollout.

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The beginning of the end for Mr Johnson stretches back some eight months when his administration was hit with scandal after scandal, and the Government struggled to put in place key policies due to the level of sleaze engulfing Westminster.

Some time before that, Johnson faced severe criticism for part of his handling of the Covid-19 pandemic and his refusal to dismiss his most senior aide, Dominic Cummings, for his now infamous lockdown-breaking trip to Barnard Castle.

The first big problem for Mr Johnson came in November last year when Tory MP Owen Paterson was investigated by the Commissioner for Parliamentary Standards after being accused of breaking lobbying rules.

The commissioner found that, on behalf of companies, Mr Paterson’s meetings with officials and ministers constituted “serious breaches” of rules.

The Prime Minister backed an overhaul of the standards system in a bid to stop Mr Paterson being suspended, but was forced into a U-turn following a furious backlash.

Mr Johnson managed to weather the political storm but his next scandal caused real anger with the British public.

Partygate brought down Health Secretary Matt Hancock and Mr Johnson’s press secretary, Allegra Stratton, but ultimately he survived.

Mr Johnson shrugged at an almighty level of criticism thrown his way for the boozy culture in Downing Street while the country was under lockdown.

He swerved calls to quit, even when he and his Chancellor were hit with fines from the police.

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Opponents thought the Sue Gray report into the Government’s drinking culture during lockdown could be the final nail in Mr Johnson’s administration.

The report bluntly stated that there were “failures of leadership and judgment in No 10 and the Cabinet Office” for which “the senior leadership at the centre, both political and official, must bear responsibility”.

But still Mr Johnson clung on.

He even enjoyed a renewed confidence on the world stage over the Ukrainian war effort, using it repeatedly as reason not to remove him from office.

But, this time, with his fate in the hands of Tory MPs, this scandal proved one too many for even Mr Johnson.