'Held to ransom' by Dominic Cummings: How Boris Johnson's late-night call helped avert mass exodus

It was a damage limitation exercise like no other. Shortly after 10pm on Wednesday, aides at Number 10 were frantically trying to contact other colleagues to persuade them not to resign.

There was a very real fear that as many as half a dozen advisers could walk out following the resignation of Lee Cain, Downing Street's head of communications, an hour earlier.

Dominic Cummings, Boris Johnson's chief adviser, had made it clear some weeks earlier that if Mr Cain resigned he would go too – and take others with him.

When staff left work at 9pm on Wednesday, shortly after Mr Cain's resignation, they believed that Oliver Lewis, Mr Johnson's deputy Brexit adviser, and possibly Mr Cummings, who are considered to be "of one mind" by colleagues, had made up their minds to go.

"Five or six" aides would have walked out if Mr Cummings had resigned, according to sources. They included Mr Lewis; Cleo Watson, the head of priorities and campaigns who is often pictured arriving for work with Mr Cummings; Ben Warner, a data scientist, and Claire King, a special adviser on operations and events who was hired by Mr Cummings.

Mr Johnson led the way in preventing the walk-out by picking up the phone to Mr Cummings, who was at home. His long-standing political secretary, Ben Gascoigne, who worked for him in London's City Hall for six years, started to ring round other aides "to make sure there wasn't going to be a walk-out", sources said.

One aide texted a friend around the same time, saying it was "50-50" whether Mr Cummings was going to stay in Government. A Tory MP who was receiving live updates told The Telegraph: "There is a big bust-up going on in Number 10. Cummings is saying: 'If I go, these people are going with me.' He is basically holding the PM to ransom."

Mr Cummings on Thursday night denied threatening to resign and asking others to do so.

He is understood to have made clear to colleagues in Downing St some weeks ago that he would consider quitting if Mr Cain was forced to go.

He and Mr Cain are understood to have grown close since Mr Cain's father died last year. Mr Cain is understood to have told friends that Mr Cummings had become like a father figure to him since then, that he spoke to him every day and that he considered him far more than just a colleague.

By 11pm it was confirmed that Lord Udny-Lister, 71 – who as Sir Eddie Lister was a close adviser to Mr Johnson in City Hall – was also leaving 10 Downing St, although his decision had been expected.

But as the calls went out over the following hour, it became clear that mass resignations had been averted. Mr Johnson is understood to have asked Mr Cummings to sleep on any decision.

It emerged that Lord Frost, currently neck deep in Brexit negotiations, was staying put. Then, just before midnight, the BBC reported that Mr Cummings was not resigning either.

A question mark remained over the future of Mr Lewis, who was said on Thursday morning to still be "close to the brink". Colleagues now think he might walk away after the Brexit negotiations are over.

For weeks, the Prime Minister had been on the hunt for a new chief to give him better grip on his Government and learn lessons from mistakes made in the handling of the coronavirus pandemic.

He had offered Mr Cain the role of chief of staff on Monday after he tendered his resignation last week. Mr Cain was understood to have wanted a change after his exhausting stint so he could see more of his young son. He was also unhappy with the appointment of Allegra Stratton as the PM's new press secretary for televised press conferences.

For days, he had also had to deny claims from MPs that he was a candidate to be the "chatty rat" who leaked details of the second national lockdown on October 30, telling friends he had been ruled out as a suspect by Simon Case, the Cabinet Secretary, who is in charge of the inquiry.

Mr Cain told Mr Johnson on Monday that he wanted some time to think about the offer and then, allies claim, was shocked to see it plastered over the front page of a newspaper 48 hours later. One said: "Lee was offered the job on Monday and by Tuesday night it was in the first editions of the papers before he had even given his answer.

"It wasn't him or anyone close to him that leaked it – it was someone who didn't want him to get the job. Why would Lee try to bounce the PM into giving him a job that was already on the table?"

It meant that just as Mr Johnson should have been preparing for his weekly joust with Sir Keir Starmer, the Labour leader, at Prime Minister's Questions, he was instead preoccupied with the leaked job offer.

MPs were incensed as they digested the news over breakfast. One said: "The lunatic will have literally taken over the asylum. He [Mr Cain] is Dom Cummings' puppet, and Dom Cummings is an advocate for lockdowns."

Mr Johnson called in Mr Cummings to discuss the leak, which some felt had been made to try to bounce the PM into confirming Mr Cain's appointment as chief of staff. By lunchtime, the BBC's political editor Laura Kuenssberg reported that Mr Cain's promotion was being opposed by Carrie Symonds, Mr Johnson's fiancee and a former Conservative Party head of communications.

Allies of Ms Symonds said she felt "uncomfortable" about the role going to Mr Cain. She was joined in her concern by Allegra Stratton, who Mr Cain had helped recruit to be the PM's new press spokesman for White House-style televised press briefings.

Both women made it clear that they were uneasy about Mr Cain's at times abrasive manner, while also questioning his communications strategy. Some sources said this led to Mr Johnson withdrawing the job offer.

The situation had not resolved itself by the early evening, when Mr Cummings left his office at Number 10 to head home. Mark Spencer, the Government chief whip, who had been particularly stung by the leak of the lockdown before Parliament could be told, was spotted in Downing Street.

At around 8pm, Mr Johnson met Mr Cain, who reportedly told the PM that he wanted the chief of staff role or he would resign. An hour later, Number 10 released his resignation statement. "It was an honour to be asked to serve as the Prime Minister's chief of staff," the statement said.

Mr Johnson responded: "I want to thank Lee for his extraordinary service to the Government over the last four years. He has been a true ally and friend, and I am very glad that he will remain director of communications until the New Year and to help restructure the operation. He will be much missed."

As a clear morning broke over Westminster on Thursday, there was some sympathy for Mr Cain. One friend said: "Lee was very close to a lot of people in 10 Downing Street. He brought them on and supported them."

Mr Cain, for his part, is staying on as director of communications until January although some officials privately doubt he will remain in post for that long if his heart is not in it.

The briefing war continued to rage, with friends of Mr Cain claiming Ms Stratton was "not the right person for a harmonious team" and allies of Ms Stratton suggesting Mr Cain should leave his post immediately because he is now a "lame duck".

Sources close to Mr Cain suggested the unhappiness in Downing Street at his departure "isn't a Vote Leave thing, it's just that some people are loyal to Lee and others are loyal to others".

The long-term position of Mr Cummings also looks less sure. Some said he wanted to stay to focus on the PM's "Moonshot" bid to mass-test the country for coronavirus, and to build a UK version of America's Advanced Research Projects Agency "to lock in his gains".

But with Mr Cain and Lord Udny-Lister exiting Mr Johnson's close circle of advisers in January, Conservative MPs are sensing a chance for the PM to appoint a heavyweight political figure who is sympathetic to their demands as chief of staff.

Sir Charles Walker, the vice-chairman of the 1922 Committee of backbench Conservative MPs, told The Telegraph: "This is a fabulous opportunity for the Prime Minister to make a great hire that puts himself firmly back at the centre of the Parliamentary party's affections.

"This is too good an opportunity to waste. The Prime Minister needs to put it to good use – and if he does, this could turn out to be a really good week."

Mr Cummings is at "the beginning of the end" of his time in Downing Street, sources said on Thursday night. He signalled that he could be gone by Christmas as he said his plan had always been to make himself "largely redundant" by the end of the year.

Asked about rumours he would be gone by Christmas, he told the BBC: "My position hasn't changed since my January blog," when he wrote that he intended to make improvements to the Downing Street operation that would mean he was no longer needed by the end of 2020.