The future of Sir Ian Blair as Commissioner of the Metropolitan Police has split the country almost evenly, according to a new Populus poll for The Times.

Middle-class and Conservative voters narrowly back Sir Ian staying on, while working class, Labour and Liberal Democrats voters believe that he should resign by a clear margin.

The poll was undertaken over the weekend, between November 2 and 4, after the Met had been found guilty by a jury of endangering the public under health and safety laws over the shooting of Jean Charles de Menezes by police officers on a Tube train in July 2005.

The officers had mistaken Mr de Menezes, a Brazilian living in London, for a possible terrorist.

After the verdict, 48 per cent of voters believe that Sir Ian should “take responsibility for his officers’ actions and should now resign”. But almost the same number, 46 per cent, disagree. (For more details see www.populus.co.uk) Support for Sir Ian’s immediate resignation varies. It is highest among Labour supporters at 55 per cent, falling to 44 per cent among Conservative voters, and 43 per cent among professionals and managers.

Moreover, more than half of working-class voters favour his early departure, with fewer than two fifths disagreeing. Men are marginally more hostile to Sir Ian than women, with 50 rather than 46 per cent wanting him to go now.

The public are, however, concerned about the nature of the trial. Two thirds (68 per cent) believe that “applying health and safety laws to police activities of this kind could make it harder for the police to prevent future terrorist attacks”.

The commissioner has so far resisted calls to resign after his force was found guilty of serious failures leading to the death of the innocent Brazilian.

Sir Ian, Britain’s top policeman, is likely to face further criticism this week as he prepares to be questioned publicly for the first time over the shooting. Tomorrow he will appear before the London Assembly. Although members had to submit their questions for the Commissioner’s annual visit by October 23, they can still ask supplementary questions. Sir Ian may also make a statement, on which he could be questioned.

On Thursday the Independent Police Complaints Commission will publish its report into the shooting at Stockwell Tube station. It is thought to have identified 15 areas of failing by Scotland Yard. It will detail for the first time the eyewitness accounts from commuters of the last seconds of the life of Mr de Menezes.

After all this, Sir Ian still has to face a vote of no confidence by the Metropolitan Police Authority.

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