When the nine members of the powerful Intelligence and Security Committee (ISC) of parliament filed into the Macmillan Room of Portcullis House at 5pm for the first meeting of the new committee, Chris Grayling thought he had the chairmanship in the bag.
After all, the former Cabinet minister and Brexiteer was Boris Johnson’s choice – controversially, given his record in government and lack of expertise on intelligence and security – and he had already nominated himself the day before.
Nothing could go wrong, he must have thought, because the Tories had a five-four majority on the nine-member committee.
But Mr Grayling and the government whips had both made a major blunder. Neither had sounded out the senior Tory backbencher Dr Julian Lewis and made sure that he was going to vote for Mr Grayling.
And when the committee clerk asked at the start of the meeting if there were any more nominations for chairman, Dr Lewis nominated himself and was immediately backed by the three Labour and one Scottish National Party member.
Result: 5-4 to Dr Lewis, leaving Mr Grayling – cruelly lampooned as “failing Grayling” after his accident-prone Cabinet career – and the prime minister humiliated, and the Number 10 machine who were so desperate to see their loyalist nomination elected absolutely furious.
“Grayling is the only person ever to have lost a rigged election,” said one Tory MP.
Mr Grayling had been ambushed. It had been a bloodless coup. But that was about to change.
Within an hour of the decisive vote in the Macmillan Room, it emerged that the committee would meet again at 10am the following morning and almost certainly agree to publish the committee’s long-suppressed report on allegations of Russian meddling in UK politics.
But a crisis for the prime minister was then immediately turned into a drama by Number 10, when Dr Lewis was informed by the government’s burly bruiser of a Chief Whip, Mark Spencer, that he had been kicked out of the Tory parliamentary party.
Dr Lewis had the whip withdrawn, government sources told Sky News, “for working with Labour and other opposition MPs for his own advantage”.
Another source said: “There are consequences for that duplicity.”
The decision sent shockwaves through Westminster.
“This is gangster politics,” one member of the committee was reported to have said.
The consensus among many MPs was that Number 10 was guilty of a massive overreaction which has made what was only a moderately bad situation much, much worse.
Dr Lewis has suffered the fate of the 21 pro-Remain Tory MPs who defied Mr Johnson in Brexit votes last year, including – in a delicious irony – the former chairman of the ISC, Dominic Grieve.
One senior MP told Sky News: “This would have blown over in a few days. Now there will be a huge row throughout the weekend and into next week.
“Removing the whip from Julian also massively strengthens his authority and boosts his independence from the government.
“He is also very popular with the Tory old guard on the back benches, the old knights of the shires, the Thatcherites and the veteran Brexiteers. He’s one of them and they won’t like it.”
Dr Lewis is indeed popular with MPs on both sides of the House.
He was a successful chairman of the Defence Select Committee for four years. He is independent-minded and, despite being a Brexiteer, was a big defender of John Bercow during the former speaker’s battles with Mr Johnson last year.
MPs blame the prime minister’s controversial adviser, Dominic Cummings, for Number 10’s brutal revenge on Dr Lewis.
“This isn’t the Chief Whip’s decision,” one senior MP told Sky News.
“It’s Cummings. And it’s absolutely bonkers.”
Number 10’s retribution against Dr Lewis may not be over, however.
The rules governing the ISC, in the Justice and Security Act of 2013, state that the chairman is elected for the whole parliament, until the next election.
But there is already talk of the government tabling a Committee of Selection motion, which can be debated for up to 90 minutes and then voted on by MPs, removing Dr Lewis from the committee and replacing him with another Tory MP.
That would cause a huge row. But would the PM, in his current belligerent mood, care?
And in the chamber, of course, Mr Johnson has a majority of 80. Well, he did. It’s down to 78 now, with Dr Lewis presumably crossing the floor to sit with the opposition.
One MP even suggested the PM could go for the nuclear option of abolishing the Intelligence and Security Committee altogether.
Out of the question? Probably not while Mr Cummings is advising Mr Johnson.
Despite his humiliation, Mr Grayling remains a member of the committee and could yet – theoretically – still become chairman if Dr Lewis is kicked of the committee and replaced by a Johnson loyalist.
Besides Mr Grayling, the other outvoted Tories are another ex-Cabinet minister Theresa Villiers, ex-minister Sir John Hayes and backbencher Mark Pritchard.
It was Labour MPs Dame Diane Johnson and Kevan Jones, Labour peer Lord West and SNP MP Steward Hosie who backed Dr Lewis.
When Dr Lewis walked into the Macmilan Room in Portcullis House at 5pm, he obviously knew he had the support of the opposition MPs on the committee.
But with Boris Johnson in vengeful mood, he may need the support of many other Tory MPs if he is to survive this fight to the death with the prime minister.