An example of his courage was displayed while investigating terrorist attacks in Northern Ireland. On returning to his hotel one evening, he was informed that a group of loyalist terrorists had discovered where he and his team were staying and were drinking in the nearby bar.
He immediately marched up to the gang and approached the leader saying: "Good evening, gentlemen, is there a problem?" The group moved on without finishing their drinks. Several were later arrested.
The 56-year-old Deputy Commissioner at Scotland Yard will need all that commitment and strength if he is to survive and thrive in what is widely considered the toughest job in policing.
He joins a 44,000-strong force at a time of huge change and turbulence. Morale is said to be at an all-time low following the battering the force's reputation took during the inquiry into the botched Stephen Lawrence murder investigation. The Yard's image was further tarnished by a very public anti-corruption inquiry in which Sir Paul Condon, the Commissioner, estimated that up to 250 officers were bent. In fact only 50 have been charged or suspended.
The crime rate in London has also started to go up, partly, officers claim, because they are scared of being labelled "racists" and have drastically reduced the number of stop and searches against black men.
Into this cauldron steps John Stevens. An officer for 35 years, he has enjoyed a glittering career during which he has received 27 commendations. He started with the Met in 1964 and quickly moved into the CID where he ran a number of murder investigations and other big inquiries, including the hunt for the spy George Blake.
He left the Met to become Assistant Chief Constable of Hampshire in 1986 before moving, two years later, to Cambridgeshire as Deputy Chief Constable. In 1991 he was appointed Chief Constable of Northumbria. In a technique he intends to replicate in London he used "intelligence-led" policing in Newcastle to combat the city's car-theft culture and reduced the crime rate by 42 per cent. In a parallel success, the crime detection rate rose by more than 20 per cent during his five-year tenure.
He left Northumbria in 1996 when he was appointed one of Her Majesty's Inspectors of Constabulary. In May last year he became second-in-command at the Met, and headed the anti-corruption drive.
Earlier this year he was appointed to re-investigate the murder of Pat Finucane, a Catholic solicitor from Belfast. In the past 10 years he has carried out three inquiries in Northern Ireland into murders and terrorist attacks by loyalist paramilitaries, allegedly aided by security force collaborators. He confronted intelligence officers who lied to him about their covert activities and went on to secure 43 convictions.
He believes the Met is facing huge changes with the creation of a new police authority which comes into power next April, taking over the Home Secretary's responsibility for the force. Other challenges include achieving new recruitment targets for ethnic minority officers, combating rising crime, and tackling low morale among his own officers.
Widely respected by his staff he is considered a "copper's copper". However, at 6ft 3in he does not suffer fools and has been criticised for being overbearing and adopting a bullying tone towards officers who fail to live up to his high standards. He has had his eye on the top job since becoming Deputy Commissioner. He remarked privately that he "didn't come down to London just to be the deputy".
Married with three children, he still has a home north of Newcastle and, as a qualified pilot, regularly flies to the North-east for weekends. Although he keeps a flat in London, he plans eventually to retire to Northumbria. A law graduate who also has a master's degree in philosophy, he is more at home in a wine bar drinking a glass of his beloved red, than a smoky pub. He is far more relaxed and easygoing than his predecessor, Sir Paul Condon, but questions remain as to whether he is wily enough to cope with the demands of the Home Office and the soon-to-be-elected mayor, and the intense media scrutiny in a post that is as much about being a successful politician as a good policeman.
So far he has maintained good relations with journalists but must know this could quickly sour with the inevitable bad news stories, cock-ups, scandals, and accusations of incompetence that will be aimed at one of the world's biggest police forces.
He was said yesterday to be "absolutely delighted" at his appointment. From 9am today, as he holds the first of a day of press and television interviews, he will get his first taste of the power and perils that come with being Commissioner.
n Stop the rise in crime, which has seen a 15 per cent increase in the London area in the past three months. Street muggings have started to go up again and violent assaults continue to rise.
n Improve morale among staff and win back public confidence. Accusations of racism and corruption have hurt officers' belief in themselves and public trust in the force.
n Recruit, retain and promote more ethnic minority officers and show that stop-and-search tactics are not random or racist.
n Sort out the finances. Payments for pensions, sickness and defamation suits are bleeding the force of vital resources.
n Cut down on drug-related crime, including murder and burglary. More selective operations to catch the culprits.Reuse content