You’re reading Reaction. To get Iain Martin’s weekly newsletter, columnists including Tim Marshall, Maggie Pagano and Adam Boulton, full access to the site and invitations to member-exclusive events, become a member HERE. 

When Dougie Smith and Munira Mirza abandon Boris Johnson, you know the game is up. In Number 10 Dougie Smith is the key Tory fixer – the man who knows where the bodies are buried and hardly ever gets mentioned by the press, for some reason. This Boris loyalist is now firmly in the “it has to be Rishi” camp, say insiders. Smith is married to Munira Mirza, who has worked for Johnson for 14 years.

Mirza resigned as head of Downing Street’s policy unit on Thursday afternoon after the Prime Minister failed to apologise for falsely accusing Sir Keir Starmer of failing to charge Jimmy Savile when he was Director of the Crown Prosecution Service.

Her departure indicates that the Johnson operation is now collapsing in on itself, and there is a rush to install the Chancellor in Number 10 before he becomes too tainted by tax hikes and inflation.

News of the resignation was broken by The Spectator’s James Forsyth, a friend of Mirza. His wife Allegra Stratton worked alongside her in Downing Street.

Prior to today, you would have struggled to find a closer confidant to the Prime Minister than Mirza, other than Smith. The Oldham-born daughter of Pakistani immigrants, Mirza worked with Johnson throughout his eight-year reign as Mayor of London.

Mirza’s unexpected departure will arguably hurt Boris more than any aide resigning or MP filing a letter of no confidence.

Here is the full letter of resignation:

“Dear Prime Minister,

It is with great regret that I am writing to resign as your Head of Policy.You are aware of the reason for my decision: I believe it was wrong for you to imply this week that Keir Starmer was personally responsible for allowing Jimmy Savile to escape justice. There was no fair or reasonable basis for that assertion. This was not the normal 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.I have served you for fourteen years and it has been a privilege to do so. You have achieved many important things both as Prime Minister and, before that, as Mayor of London. You are a man of extraordinary abilities with a unique talent for connecting with people.You are a better man than many of your detractors will ever understand which is why it is desperately sad that you let yourself down by making a scurrilous accusation against the Leader of the Opposition.Even now, I hope you find it in yourself to apologise for a grave error of judgement made under huge pressure. I appreciate that our political culture is not forgiving when people say sorry, but regardless, it is the right thing to do. It is not too late for you but, I’m sorry to say, it is too late for me.

Yours sincerely, Munira.”