Four senior aides quit Prime Minister Boris Johnson's team

Boris Johnson’s leadership has been further thrown into crisis by the resignation of four key aides as Chancellor Rishi Sunak criticised the Prime Minister during a broadcast from No 10.

Munira Mirza, who had been one of the PM’s most loyal and longstanding advisers, quit over his use of a “scurrilous” Jimmy Savile smear.

She told the Prime Minister she was departing as No 10’s head of policy because he refused to apologise for the widely criticised attempt to tarnish Sir Keir Starmer.

Then came the resignation of Jack Doyle, No 10’s director of commutations who was embroiled in allegations of lockdown-breaching parties in Downing Street.

Number 10 later revealed on Thursday night that both Dan Rosenfield, the prime minister’s chief of staff, and Martin Reynolds, Johnson’s principal private secretary, are also leaving their roles.

Reynolds will return to the Foreign Office, officials said.

Meanwhile, in a live broadcast on the cost-of-living crisis, Sunak praised Mirza as a “valued colleague” and criticised the Prime Minister’s Savile remarks, saying: “I wouldn’t have said it.”

Earlier in the day, the Chancellor did not rule out a leadership bid if Tory MPs force out Johnson over allegations of lockdown-breaching parties in Downing Street.

Johnson backtracked on the debunked claim that the Labour leader failed to prosecute Savile while director of public prosecutions (DPP).

But Mirza, who first advised him as London mayor more than a decade ago, said she was quitting after the Prime Minister stopped short of giving the apology she demanded.

“I believe it was wrong for you to imply this week that Keir Starmer was personally responsible for allowing Jimmy Savile to escape justice,” a letter seen by The Spectator magazine read.

“There was no fair or reasonable basis for that assertion. This was not the usual cut and thrust of politics; it was an inappropriate and partisan reference to a horrendous case of child sex abuse. You tried to clarify your position today but, despite my urging, you did not apologise for the misleading impression you gave.

“You are a better man than many of your detractors will ever understand, which is why it is so desperately sad that you let yourself down by making a scurrilous accusation against the Leader of the Opposition.”

Johnson, who once praised Mirza as a “brilliant thinker” and listed her as one of the five women who had influenced and inspired him the most, denied his Savile smear was inappropriate.

But he told Channel 5 News: “I’m sorry to lose Munira, she’s done an outstanding job, she’s been a wonderful colleague for a long time.”

Tory MP Andrew Griffith was swiftly appointed to fill her role.

Doyle gave a resignation speech to staff in No 10, saying “recent weeks have taken a terrible toll on my family life” but that he always intended to resign after two years in the role, according to the Daily Mail, who he used to work for.

The former journalist reportedly attended at least two of the 12 events in Downing Street and wider UK Government that are under investigation by police.

A No 10 spokesman said: “Jack Doyle has left government. He has made a huge contribution and the Prime Minister is immensely grateful for the work he has done.”

Meanwhile, Mayor of the West Midlands Andy Street, seen as key in winning Tory votes outside the traditional heartlands, declined to give his full support to Johnson, saying his actions were “bad by any measure”.

In an interview with the Birmingham Mail, Street said: “The honest answer is that we are waiting to see if he follows through on what he’s now said.”

The resignations left the Prime Minister further isolated as he battles to remain leader, with 13 Conservatives having publicly called for his resignation over “partygate”.

More are believed to have done so privately, but the number of letters to the chair of the 1922 Committee of Tories has not yet hit the 54 required to trigger a no confidence vote.

The Chancellor was asked about Mirza’s resignation and Johnson’s remarks while appearing at a press conference in No 10 after setting out emergency measures to help people struggling with soaring energy bills.

“She was a valued colleague. I very much enjoyed working with her and I’m sorry to see her leave government. I’ll miss working with her,” Sunak said.

“With regards to the comments, being honest I wouldn’t have said it and I’m glad the Prime Minister clarified what he meant.”

Asked if he thinks the PM should apologise, Sunak said: “That’s for the Prime Minister to decide.”

Dominic Cummings, the former chief aide to No 10 who is agitating for the Prime Minister’s removal, said Mirza’s resignation was an “unmistakable signal the bunker is collapsing”, adding that the “PM is finished”.

On Monday, Johnson accused Sir Keir of having “used his time prosecuting journalists and failing to prosecute Jimmy Savile” as he came under huge pressure in the Commons over Sue Gray’s report into alleged lockdown breaches.

Under pressure from Tory MPs and lawyers representing Savile victims, the Prime Minister tried to backtrack his claim on Thursday.

He insisted he had not been referring to Sir Keir’s “personal record” as he acknowledged “a lot of people have got very hot under the collar”.

“Let’s be absolutely clear, I’m talking not about the Leader of the Opposition’s personal record when he was DPP and I totally understand that he had nothing to do personally with those decisions,” he told broadcasters in Blackpool.

Sir Keir apologised while DPP in 2013 for the Crown Prosecution Service having failed to bring Savile to justice four years earlier.

But there is no evidence that Sir Keir had any personal role in the failure to prosecute the man who was one of Britain’s most egregious sex offenders before his death in 2011.

The Labour leader has accused Johnson of “parroting the conspiracy theories of violent fascists to try to score cheap political points”.

Johnson’s retreat came despite numerous Cabinet ministers being sent out to defend the remarks.

There were questions over whether Dougie Smith, who is Mirza’s husband, will also quit as an aide to No 10.

Earlier in the day, Sunak insisted the prospect of a leadership contest remained a “hypothetical situation” and the Prime Minister had his full support.

But, seen as a likely frontrunner, he acknowledged in a BBC interview that some Conservative MPs would like to see him replace Johnson in No 10.

“Well, that’s very kind of them to suggest that, but what I think people want from me is to focus on my job,” he said.

“I know a few of my colleagues have said that and they’ll have their reasons for doing that, but I don’t think that’s the situation we’re in.

“The Prime Minister has my full support. And what people want from me is to be getting on with my job, which is what I’m doing.”

Three more Tory MPs disclosed publicly on Wednesday that they had submitted letters calling for a vote of no confidence in the Prime Minister.

Others are thought to be waiting for the publication of the Gray inquiry, which has been delayed due to the ongoing Metropolitan Police investigation into 12 gatherings over the course of 2020 and 2021.