Sir John Stevens, who leaves his post as Metropolitan Police Commissioner on Monday, has been credited with turning the force's fortunes around.
Sir John has increased the number of officers in the Met Police
He took control of the Met in 2000 soon after the Macpherson Report - into the Stephen Lawrence murder inquiry - branded it "institutionally racist".
Since then Sir John, 62, who joined the police in 1962, has boosted morale and numbers of ethnic minority and female officers.
Tony Blair has also commended him for keeping the country safe from a terror attack.
The prime minister made the comment at a reception to mark Sir John's retirement at Scotland Yard earlier this week.
Sir John's down-to-earth approach is said to have helped with the flagging morale of officers in the aftermath of the Macpherson report.
Sickness has plummeted among Met Police staff over the past five years and the overall number of officers has grown from 25,000 to 30,000.
Sir John has an impressive career history, having been commended 27 times for outstanding detective ability and courage.
But his lowest point was when he stood trial after the Health and Safety Executive (HSE) accused him of breaching safety regulations after two officers fell through roofs while chasing suspects.
Both Sir John, and his predecessor Lord Condon, were cleared of all charges.
More recently he has spoken out about the rise of binge-drinking and its impact on increasing violent crime and disorder.
The outgoing police chief has also called for urgent action to curb knife attacks, as well as asking for clarification on the rights of householders to defend themselves in their own homes.
The Met celebrated its 175th anniversary under Sir John in 2004.
But his retirement from the Commissioner's role will not be the end of his police career as he will continue to lead the inquiry into Princess Diana's death.
Sir John has been known as the face of British policing for his openness with the media and straight talking.
He said, after pro-hunt demonstrators clashed with police outside the House of Commons last September: "No one got cracked over the head for no reason."
The married father-of-three started his career patrolling the streets of west London as a Pc but made his name while deputy chief constable of Cambridgeshire.
He went to Northern Ireland to investigate claims of collusion between loyalist paramilitaries and the security forces.
Sir John has also seen burglaries and street crime fall while being Britain's most senior policeman - the job which he once described as "the best in the world".