Why is the Mayor so keen to defend Met chief?

Ken Livingstone has been the biggest defender of Sir Ian Blair, issuing press statements and taking to the airwaves and television to give him unequivocal support.

This contrasts with the Mayor's Left-wing past at the GLC and as an MP, when he would invariably take the side of constituents - often Irish - who claimed persecution from the state.

The Mayor also has a far more even relationship with Sir Ian than he did with his predecessor, Sir John Stevens, who appeared to intimidate him. By the time Sir Ian took the post two-and-a-half years ago, Mr Livingstone had had five years in the job with a wealth of experience.

In the past week the Mayor has appeared on Radio 4's Today programme and made himself available for BBC London to interview at short notice. He also used a substantial part of his weekly press conference to speak up for Sir Ian.

Within minutes of the London Assembly passing its motion calling on the Met Commissioner to be sacked, the Mayor's officials were handing journalists a strongly-worded statement denigrating the Assembly and saying the vote had merely handed a propaganda victory to the terrorists. He accused Assembly members - for whom he has increasing contempt - of "skulking around in plots" trying to whip up a media storm to unseat the Commissioner.

The Mayor also made repeated attacks on Tory shadow home secretary David Davis, contrasting his calls for Sir Ian to resign with his earlier support for the John Major government that cut Met funding.

Last year, facing Tory accusations that Sir Ian had "opened his mouth and only engaged his brain later", Mr Livingstone compared the public attention experienced by the Commissioner to that he had to endure as Mayor. Mr Livingstone said: "I would say what I have said many times: Sir Ian Blair is London's best chance of creating a modern and efficient police force." He also praised the Met's recruitment of ethnic minorities, saying it was getting closer to reflecting the diversity of Londoners. I suspect the fact that, for the first time in our history, the majority of people applying to join the police are black or Asian is an indication that the public of London recognise the police have changed. I just wish the newspapers were changing as fast as the police."

At the heart of the Mayor's relationship with Sir Ian is their mutual belief in putting police back on the beat.

Sir Ian is credited with devising neighbourhood policing, the system which gives every one of London's 620 council wards its own dedicated team of six or more officers and community support officers. The Mayor managed to find the money - and Sir Ian the officers - to have neighbourhood policing rolled out two years ahead of schedule.

Mr Livingstone can often be heard eulogising about his childhood in Fifties London when police constables would clip troublemakers round the ear for scrumping for apples or misbehaving. He blames Sixties TV show Z-Cars for putting police in "panda cars" and off the beat, a move the safer neighbourhood teams is meant to reverse.

The Mayor welcomes the greater attention paid to police financing, which he said had been a disaster "for the last 100 years" with an absence of even basic book-keeping. This year one of City Hall's most senior bean-counters, Anne McMeel, was appointed Met treasurer. Mr Livingstone also defended Sir Ian's public appearances, from giving the Richard Dimbleby lecture to appearing on BBC TV's Question Time. He said: "The Commissioner of Police in this city has most probably almost as much power as I do, and perhaps even more - as much power as a Cabinet minister.

"He is not party political but he has huge roles and responsibilities, he affects the lives of every citizen of this city all the time, he is bound to be in the public eye, he has to be accountable and there will always be controversy around any commissioner who is doing his job."

When Sir Ian described the media as "institutionally racist" for its handling of the Tom ap Rhys Pryce case and the relative under-reporting of the murder of an Asian man in Newham, Mr Livingstone again backed him, saying he had "rightly highlighted that certain sections of the media are not immune from racism".

Previously, over the de Menezes case, the Mayor said he would "lock him in the room" to prevent Sir Ian resigning. He has given the Commissioner frequent space in his free monthly newspaper, The Londoner, to publicise his achievements and an easy ride on controversial plans, such as the closure of police stations and merger of key police units. This started when Sir Ian was Deputy Commissioner.