Blair forced out of Met; The World Today POLICING: Top cop fails to get backing of mayor.

SIR IAN BLAIR sensationally quit as Metropolitan Police Commissioner after failing to get the backing of London mayor Boris Johnson.

Britain's most senior police officer said the mayor had told him he wanted a "change in leadership" at the top of the Met.

Sir Ian said: "Without the mayor's backing I do not think I can continue in the job."

Mr Johnson took over as chair of the Metropolitan Police Authority on Wednesday.

Sir Ian defended his record at the top of the Met and said it was the duty of the Commissioner to lead the force "through good times and bad".

He said he would leave the job on December 1 after Home Secretary Jacqui Smith had "reluctantly but graciously" accepted his resignation.

"I am resigning not because of any failures of my service and not because the pressures of the office and the many stories that surround it are too much," he said.

"I am resigning in the best interests of the people of London and of the Metropolitan Police Service.

Mr Johnson has pointedly failed to back Sir Ian since he took over at City Hall, and was due to chair his first meeting of the Metropolitan Police Authority (MPA) on Monday.