Having rid himself of one troublesome police chief, Boris Johnson, the Mayor of London, raged yesterday at another. He spoke “in trenchant terms” to Sir Paul Stephenson, the Acting Metropolitan Police Commissioner, after being told on Thursday that Damian Green was to be arrested.

Sir Paul was seen as the Mayor’s preferred choice to succeed Sir Ian Blair, but the Green affair may well dent his chances. Mr Johnson said he found it “hard to believe” that anti-terrorism police had been used to “target an elected representative of Parliament for no greater crime than allegedly receiving leaked documents”.

A spokesman for Mr Johnson said: “The Mayor told the new acting commissioner that he would need to see convincing evidence that this action was necessary and proportionate. He suggested that this is not the common-sense policing that people want when London faces a real terror threat.”

Scotland Yard sources said the decision to arrest Mr Green was taken by Assistant Commissioner Bob Quick, head of Specialist Operations, who is understood to have acted on advice from the Crown Prosecution Service.

Police sources said that their inquiry had been instigated by a request from the Cabinet Office and was handled by Counter-Terrorism Command. Mr Johnson was informed as chairman of the Metropolitan Police Authority.

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