Munira Mirza’s resignation suggests the game is up for Boris Johnson

The departure of the head of his policy unit is another serious blow for the prime minister, writes John Rentoul

Boris Johnson walking out of Downing Street with Munira Mirza (PA)

She may be unknown to most voters, but Munira Mirza’s resignation yesterday was the breaking of another pit-prop under Boris Johnson’s creaking premiership. She was head of the policy unit and didn’t organise or attend any of the lockdown-breaking gatherings, so she wasn’t part of the clearout of No 10 that the prime minister had already promised.

Johnson tried to make it look as if she was, by bringing forward the announcement of the departures of Jack Doyle, Dan Rosenfield and Martin Reynolds, three officials who had already been selected to carry the can for gardengate, as the scandal should really be called.

Her departure was different. It exposed what a mistake it was for Johnson to “imply this week that Keir Starmer was personally responsible for allowing Jimmy Savile to escape justice”, as Mirza put it in her resignation letter. The prime minister had discussed using Starmer’s record as director of public prosecutions in his response to Sue Gray’s update on her gardengate investigation on Monday. Mirza, supported by others, strongly advised against it, but Johnson went ahead with it anyway.

Mirza then asked Johnson to apologise, but in his TV interview yesterday, although he said he had not commented on the “personal involvement of the leader of the opposition in the handling of that case”, he failed to do so. She resigned, and in a public way designed to damage the prime minister.

The significance is twofold. One is that Conservative MPs will be less reluctant to send their letters expressing no confidence in Johnson. If they were constrained by loyalty, or a feeling that the prime minister had not yet had a definitive finding against him from Gray or the Metropolitan Police, Mirza’s letter has weakened their bonds. Many Tory MPs – even some surprising suspects who usually subscribe to the doctrine “all’s fair in politics” – think the Savile reference wasn’t a “decent” thing to do. It was, as Starmer said on Wednesday, beneath the dignity of the office of prime minister. It had nothing to do with Gray’s update, and was a gratuitous attempt to associate Starmer with “a horrendous case of child sex abuse”, as Mirza wrote.

What is more, it alarms Tory MPs who think that they will have to defend Johnson’s words in the next interview they do. It reminds some of them of the times when they defended the prime minister only to find that he had U-turned, and it makes many of them fearful about what Johnson is going to say next that they may have to explain at short notice.

They will not all deal with it as adroitly as Rishi Sunak, chancellor and frontrunner to replace the prime minister, at his news conference yesterday: “Being honest, I wouldn’t have said it, and I’m glad the PM has clarified what he meant.” Greg Hands, the minister who did this morning’s media round, for example, could only say: “My job is the energy minister; you don’t have to have an opinion on everything.”

The other significance of Mirza’s departure – and that of Elena Narozanski, one of the policy unit staff, this morning – is that it suggests that some people in No 10 think it’s all over. I am sure that Mirza’s anger about the Savile slur is genuine, but it is also true that if you want another job, it might be better to get out now on a point of principle than to hope for a place on the last helicopter out of Saigon.

As someone who thought that Tony Blair was unfairly and prematurely pushed out of No 10, I remember railing against endless commentary about how his “authority is draining away”, but it was true. Once the assumption takes hold among MPs, journalists and the wider public that a prime minister is on the way out, it becomes harder for them to get anything done, and to stop people leaving, and to prevent other people gravitating towards the likely successor.

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We do not know exactly when the end will come for Johnson, but I think it will be sudden when it happens. There are about 14 Tory MPs who have publicly called for him to go, even if only seven of them say publicly that they have written a letter to Sir Graham Brady, who is the only person who knows. The day before Sir Graham announced that he had received the 48 letters that were needed then to trigger a vote of confidence in Theresa May in December 2018, there were 26 MPs who had publicly said that they had written to him. That suggests that there might be twice as many letters as we know about, in which case the trigger point of 54 is still some way off.

But yesterday, it came closer. And yesterday meant that, when a confidence vote is triggered, Johnson is more likely to lose it. Being forced to deliver an imperial thumbs up or thumbs down in the privacy of a secret ballot, I think a majority of Tory MPs will think, “End it now.”

Meanwhile, the prime minister’s authority continues to drain away.