Boris Johnson’s long-term ally Munira Mirza has quit in outrage over his “inappropriate and partisan” slur involving Jimmy Savile.

But who is Ms Mirza, whom the Prime Minister once placed beside Boudicca and his grandmother as the women who most inspired him, and what does her departure mean for the PM’s future?

Ms Mirza first worked for the Prime Minister at least 13 years ago, but her background is not one that would traditionally be seen to lead to Conservatism. She is the youngest daughter of Pakistani immigrants, her father a factory worker and her mother a housewife and Urdu teacher.

Ms Mirza grew up in Oldham and attended state schools before becoming the only student at her sixth form to win a place at Oxford.

It was during her study at Mansfield College that she joined the Revolutionary Communist Party (RCP), contributing to its magazine Living Marxism.

She went on to study for a PhD in sociology at the University of Kent under Professor Frank Furedi, who co-founded the RCP, which had then dissolved.

She had various jobs in the culture and charity sectors, including at the Royal Society of Arts, the Policy Exchange think tank, and the Tate, before being made arts adviser to Mr Johnson aged 30, when he was elected as Mayor of London in 2008.

During Mr Johnson’s time at City Hall, she was promoted, in 2012, to the deputy mayor for education and culture, and was described by his former head of communications at City Hall Guto Harri as “the perfect counter to those critics who suspected the worse of Boris”.

Ms Mirza is reported to have been a supporter of Brexit far before Mr Johnson, and once joined a protest against a ban on drinking on the London Underground which involved riding around the Circle Line while day drinking, in an objection to the state dictating such a move.

In 2018, when the Prime Minister’s comments about women in burkas hit the headlines, Ms Mirza – a Muslim – launched a passionate defence of him in the media.

Ms Mirza reportedly helped write the manifesto that got Mr Johnson to No 10. Once he became Prime Minister, she was brought in immediately as one of his inner circle.

Ms Mirza has mainly stayed out of the limelight, until she was revealed as playing a major role in the setting up of the PM’s commission on racial disparity in 2020, following the Black Lives Mater demonstrations.

Critics said she was the wrong person for the job as she had previously questioned the existence of institutional racism and hit out at a “culture of grievance” among anti-racism campaigners.

But Mr Johnson defended her in the Commons as “a brilliant thinker about these issues”.

In a profile of Ms Mirza and her husband Dougie Smith – also a powerful force in the Tory party – The Daily Telegraph reported how she had, as recently as December 2018, described herself as “left-wing”.

Ms Mirza was listed by Mr Johnson in 2020 as one of the top five women who had inspired him.

She was on the list along with campaigner Malala Yousafzai, his grandmother, queen of the British Iceni tribe Boudicca, and singer/songwriter Kate Bush.

Of Ms Mirza he said: “Munira is capable of being hip, cool, groovy and generally on trend.”

The departure of Ms Mirza from No 10 comes after a growing number of Conservatives said they had lost confidence in Mr Johnson.

She has been replaced as head of the policy unit by MP Andrew Griffith.