At the height of his power in early 2020, Boris Johnson was asked to compile a list of the five women who had most influenced his life. One he noted was Munira Mirza, director of his No. 10 policy unit, who had served as deputy mayor for culture during his time as mayor of London. For anyone who knew "Planet Boris” from its origins, Mirza was the guiding intellect of the Johnson project: a savvy, quiet figure using the role of London figurehead to launch his bid for leadership of the Conservative party — and ultimately, his power grab as prime minister.

After a brief stint in the arts sector, Mirza returned to the political front lines at No. 10, delivering the government’s agenda, but also shaping it as a northern meritocrat distanced from Johnson’s coterie of elite friends. She was, the prime minister said, the "most powerful nonsense detector” he knew.

Now she has resigned after objecting to her boss’s recent claim that Keir Starmer, the Labour opposition leader, was responsible in his former role as director of public prosecutions for allowing serial sex abuser and pedophile Jimmy Savile to go free of criminal charges. Johnson has "clarified” his words but offered no formal apology.