Outgoing Scotland Yard chief Sir Ian Blair has urged politicians to give senior officers more "breathing room" to run their forces.

Sir Ian said frontline policing was a high-risk business and Scotland Yard must "move on" from its "occasional disasters".

Speaking on his last day in office, he said running the £3.5 billion organisation of some 50,000 employees has been "99 per cent enjoyable".

But he admitted many will focus on the other 1 per cent, including the death of Jean Charles de Menezes, the Forest Gate raids and a string of apparent gaffes.

Sir Ian said crime had fallen by almost a fifth during his 46 months in charge, with significant reductions in violent crime and murders as public confidence in police soars.

He said the Met's response to the July 2005 attacks was one of his proudest moments and he considers Mr de Menezes the 53rd victim of the terrorists.

But he warned his successor will not only have to battle the threat of terrorism and spiralling teenage murders, but the increasing politicisation of policing.

Sir Ian said two decades ago high-profile police incidents were once treated as a matter for senior officers alone.

He said: "That is not where we are now. That has changed out of all recognition because crime is so significant.

"I think what we need is both of the major parties to give the police a bit more breathing room and recognise how extraordinary the achievements are.

"An unarmed service, reducing crime at a rate that has never been seen before, with public confidence going up, battling terror at one end and antisocial behaviour at the other.

"Now those are the areas we want to be concentrating on, not specific events, specific failures.

"The Met, for instance, has over the years I have been in it, had its occasional disasters. That is the business we are in and we have to accept those and move on."

Sir Ian's comments came after he blasted Tory London Mayor Boris Johnson for forcing him to resign after taking charge of the Metropolitan Police Authority.

He said standing down was the "only honourable course", despite retaining the support of Home Secretary Jacqui Smith, when Mr Johnson said he did not support him.

The officer admitted the upper reaches of Britain's largest force have "got a bit like politics" with one side briefing against the other.

Asked about his relationship with Mr Johnson, Sir Ian said: "I don't see myself as a victim. I don't see him as a villain. As I said before, I just see this as there comes a moment when you have to take hard choices."

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