Analysis: Increasing doubts in the corridors of power

For years he has survived a succession of gaffes and questions about his judgment ranging from his illicit recording of telephone calls with the Attorney General to his questioning of all the fuss over the Soham murders.

He has never achieved the "man of the people" popularity of his predecessor, Sir John Stevens, while his biggest test was the Stockwell shooting of innocent Brazilian electrician Jean Charles de Menezes. His admission that he was not informed and did not know his officers had shot an innocent man until 24 hours later was hugely damaging.

He has survived so far by trading on his undoubted success in reducing crime, although a shocking 18 months of record teenage murder figures has tarnished this.

The summer of controversies, including the Tarique Ghaffur allegations of race bias at the Yard, and accusations of possible irregularities over the awarding of contracts to a friend of Sir Ian's, have left many officials and officers thinking "enough is enough". Support among even some of his former friends is failing and there are rumoured to be increasing doubts at the Home Office and the Association of Chief Police Officers.

Crucially, there is also a change of administration at City Hall and, as one source says, a change of focus away from Sir Ian towards his deputy. One argument is that the Stockwell inquest is the perfect time to draw a line under Sir Ian's leadership.

If he was to be asked to step down it would be almost unprecedented. Not since James Monro resigned in 1890, after failing to catch Jack the Ripper, has a commissioner quit before serving out his time.