Detailed: How Boris Johnson was brought to his knees by the 'cuckoo nest plot'
Sir Lynton Crosby, Boris Johnson's campaign manager, was making final preparations for the formal announcement of Mr Johnson's Tory leadership bid when his phone rang at 8.53 yesterday morning.
"Hi Lynton, it's Michael Gove here," said the voice on the other end. "I'm running." "Running what?" Sir Lynton replied. "I'm running for the leadership myself." Sir Lynton was stunned. With two hours to go until the launch of Mr Johnson's leadership bid, Mr Gove, the man who was supposed to be making up the "dream ticket" with him, had not so much stabbed him in the back as run him through with a pike.
Sir Lynton asked Mr Gove whether he had told Mr Johnson. He had not, but said he intended to. The call, however, was never made.
By noon, Mr Johnson, the front-runner for the Tory leadership, was no longer a runner at all, ousted by what was being called a "cuckoo nest plot".
Having been stitched up by his running mate and several other "supporters", he threw in the towel, his ambitions in ruins. Mr Johnson's most loyal friends were apoplectic. One described Mr Gove's behaviour as "utter treachery", and suspicions quickly surfaced that Mr Gove had intended all along to use the popular Mr Johnson to win the referendum vote before ambushing him at the last moment.
It is no secret that Mr Johnson had been broadly supportive of Europe before the referendum campaign began, and that David Cameron had expected to rely on his support for Remain.
Mr Johnson, though, fell for the persuasive powers of a certain Michael Gove in deciding he was, after all, in favour of leaving the EU.
At what is rapidly becoming an infamous dinner party at Mr Johnson's home on February 16, Mr Johnson, Mr Gove and their wives sat down with the newspaper owner Evgeny Lebedev to discuss politics.
Mr Gove's wife Sarah Vine described how: "Boris was very agitated, genuinely tortured as to which way to go." It seems that by the end of the night Mr Gove, a lifelong Eurosceptic with an "obsession" for getting Britain out of Europe, had persuaded him which side of the fence he should come down on. Mr Johnson knew he was risking everything, but the potential prize was too tempting to ignore: win the EU referendum, and the keys to Number 10 would surely be his.
Once he had committed to the cause, Mr Johnson was a formidable campaigner, with his uncanny knack of connecting with voters of every background and every hue. Yet doubts quickly surfaced about just what Mr Gove was up to.
He had weekly dinners with Mr Osborne. Mr Johnson surely wondered why. He got part of the answer on Sunday, when Mr Gove's camp briefed journalists that Mr Osborne could remain as Chancellor in a Boris Johnson Cabinet. Mr Johnson dismissed the claim out of hand, but it was the first outward sign of serious differences in the victorious Leave camp.
Tension had started building the previous night in a phone call between Mr Gove and Mr Johnson. Mr Gove "demanded to be chancellor" in a Johnson government, according to one source. Mr Johnson agreed, but drew the line when Mr Gove said he wanted his chief of staff to be Dominic Cummings, his former special adviser at the Department of Education and a key strategist in the Leave campaign. Mr Cummings is a controversial and at times divisive figure, and Mr Johnson put his foot down.
There were further suspicions that Mr Gove was playing games when the Leave campaigners came together at Mr Johnson's Oxfordshire home at lunchtime on Sunday. ITV News cameras showed up to film people arriving, and one journalist let slip that they had been tipped off by Sarah Vine. Still, Mr Gove was saying all the right things. He told Mr Johnson: "I do not have what it takes and I do not have the qualities to be prime minister."
No danger there then.
On Monday, though, Mr Johnson provided more evidence of differences among Brexiteers with a newspaper column that claimed Britain would remain a member of the EU's single market. Leave campaigners began to think that Mr Johnson had gone soft on Brexit, though sources close to Mr Johnson insist the article was co-edited by Mr Gove. Was he setting Mr Johnson up for a fall?
Mr Gove and, as we now know, his wife considered their next move. With a meeting between Mr Gove and Mr Johnson in the diary for Tuesday, Ms Vine emailed her husband to say: "You MUST have SPECIFIC assurances from Boris OTHERWISE you cannot guarantee your support." The email was leaked to Sky News after being "accidentally" sent to a member of the public, making the rift front-page news.
Wednesday brought an even more significant meeting, this time between Mr Johnson and Andrea Leadsom, the highly-regarded energy minister and Leave campaigner. Mr Johnson and his key ally Dominic Raab had been hoping to convince her to give up her own leadership ambitions and throw her weight behind his campaign.
Mr Johnson left the meeting believing he had succeeded. Insiders said Ms Leadsom had signed a letter supporting his leadership bid. She would be unveiled as the big surprise at his launch event, with Mr Gove introducing her as the newest convert, and Ms Leadsom introducing Mr Johnson.
The invitations to Mr Johnson's launch event were duly texted to journalists by Mr Gove's special adviser Henry Newman.
That evening, the Conservative Party's Summer Ball was held at the Hurlingham Club in London. Mr Johnson had 97 MPs unofficially backing him by then, but his supporters were worried it would not be enough if the Tories' 200-plus other MPs united behind a "stop Boris" candidate.
Mr Cameron used the ball to make a speech in which he thanked his predecessors for their support, and hoped his successor would enjoy the same relationship (knowing full well that Sir John Major had told the Andrew Marr programme that Mr Johnson should not be PM).
After the ball Mr Gove and his wife returned to their home in Ladbroke Grove, west London, with Mr Gove's three special advisers Henry Cook, Henry Newman and Beth Armstrong, as well as a surprise guest: Nick Boles, the business minister and key Boris backer. At 5.30pm that day Mr Boles had been at the home of Nigel Adams MP, working on Mr Johnson's campaign. At 11.30pm, according to one report, he was seen helping Mr Johnson into his car after the ball.
Now, as midnight approached, he was deep in conversation with Mr Gove, conspiratorially discussing whether Mr Johnson was a busted flush. According to one account, Mr Boles and Mr Gove also knew by then that Ms Leadsom had changed her mind about backing Mr Johnson.
Mr Gove said Ms Leadsom's decision, coupled with Mr Johnson's "Brexit lite" stance, had convinced him that Boris had to be stopped, and he was the man to do it. "Events since last Thursday have weighed heavily with me," Mr Gove said in a statement yesterday. "I have come, reluctantly, to the conclusion that Boris cannot provide the leadership or build the team for the task ahead."
All of a sudden, the leaking of the Sarah Vine email did not seem so accidental after all.
With two hours to go until Mr Johnson's launch event, support for him was starting to collapse. One Johnson supporter said: "He hasn't been double crossed, he has been triple crossed. This seems to have been a pretty well developed, quite creepy operation." Over at camp Boris, MPs were withdrawing their support by the minute. The 97 backing him were now down to 47, and Mr Johnson's team realised they had been undone by what they referred to as a "cuckoo nest plot". For months Mr Johnson had nurtured Mr Gove's grand plan for Brexit, only to be kicked out when it finally hatched.
Mr Johnson, feeling "sad, disappointed and betrayed", according to one source, decided he could not go on. "It would split the party." He could muster just 25 MPs to attend his announcement, all of whom arrived in the Cloister Room at St Ermin's Hotel thinking they were backing the next prime minister.
None of them had any idea of what was about to happen.