The law must change to prevent another Metropolitan Police commissioner being forced out by London's mayor, the outgoing chief of the force has said.
Sir Ian Blair quit in October, saying he did not have the support of Boris Johnson, who was elected mayor in May.
Speaking in his final interview, Sir Ian warned against politicians trying to hire and fire police chiefs.
London's mayor has no power over the commissioner, but Mr Johnson had become chairman of the Met's police authority.
The Metropolitan Police Authority (MPA), which oversees the force and approves its strategies and spending, has been chaired by the mayor since the law was changed earlier this year.
The mayor leads public scrutiny of the force and Sir Ian said that without Mr Johnson's support for his position, business would have become impossible had he not quit.
He said he quit to protect the Met from a damaging row.
It was a very political move by him and an imitation of New York
Sir Ian Blair on Boris Johnson
It is the home secretary who appoints the commissioner because the post combines local policing duties with national responsibilities, including counter-terrorism and security.
"It was a very political move by [Mr Johnson] and an imitation of New York," Sir Ian said.
"During the 20th Century, there were 16 Metropolitan Police commissioners. There were 40 in New York as they came and went at the direction of the mayor.
"That's not the British system. It does not take sufficient account of the other burdens of this office, in terms of national security, and I hope that it's something that won't be repeated.
"I am a public servant and he [the mayor] has a very large majority. I don't happen to like the way he has used it, but… I had no choice."
He said it was a choice that had not pleased Home Secretary Jacqui Smith, but added that she could see there were circumstances in which "the way the political settlement has been laid in London that this is the possibility".
He added: "I think someone will have to look at the legislation because it's quite easy to imagine it happening exactly the other way around in four or eight years' time. And I don't think that's a good plan."
Sir Ian said he had spoken to "two or three" senior police officers who he expected to apply for the commissioner's post and told them that they had to be "resolute" in how they approached the post because of what had happened to him.
"I said in one early interview [after his 2005 appointment] that you need copper-bottomed trousers to be in this office and I can only suggest that he or she gets a pair pretty soon," he added.
Sir Ian Blair said the most pressing problem for London's policing was the 31 killings of young people during 2008.
And turning to the murder of Stephen Lawrence, he said: "The case is not closed. They should be worried that we will pursue [the killers] to the ends of their lives. We will keep doing that."
Sir Ian and Mr Johnson came face-to-face at the outgoing commissioner's last meeting with the MPA on Thursday.
Speaking at City Hall in London, Mr Johnson described Sir Ian as "a very distinguished public servant" and "one of the most thoughtful minds in modern policing".
The mayor said Sir Ian's "enormous contribution" to policing and public safety included the "magnificent" way the Met responded to the 7 July 2005 bombings.
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