Sir John Stevens likes to get out and about, to see his city for himself. Sometimes he manages to do that incognito; other times, he says, "I've got people looking after me" - which is hardly surprising, given his job as Commissioner of the Metropolitan Police for the past five years. Stevens says that on his most recent walkabout, in Charlotte Street in central London, where he was a beat officer 42 years ago, he was taken aback by the wealth of elegant restaurants. Two months earlier he had been walking down Brick Lane, in the East End, and had seen similar prosperity. "But as soon as I turned into a side road and into an estate, I saw the contrast." That contrast is "dangerous", he says. "In the world we live in, envy - a feeling of injustice - is something we need to take account of."
Police chiefs are not what they used to be. They are highly political figures, although they insist they are not politicised. I ask Stevens if he agrees with a fellow chief constable who argued not long ago that the best way to tackle crime was to narrow the gap between rich and poor. "Redistribution of wealth has always been an issue," he says, "but I'd also say that's not the full picture." Equally important is "to allow people the opportunity in a meritocracy to get their own hands on wealth through their own effort and brains". Several communities are not getting or not using those opportunities, he says.
Since announcing his decision to retire next January, Stevens has received just about as good a press as a public figure can get in the modern media environment. Affable and eager to impress, he is keen to parade the Met's achievements, and by extension his own, having in his five years turned around a force that had been deemed "institutionally racist" in the Macpherson report of 1999 and whose morale was low. Visitors to his capacious eighth-floor suite at New Scotland Yard are bombarded with statistics - robberies down, burglaries down, vehicle theft down, overall crime down, public approval ratings up.
"The level of trust, from every survey, is the highest it has been since 1995," Stevens says, proclaiming that four in five Londoners now have confidence in their police force. This contrasts with the lack of public confidence in politicians. "The politicians that I come across try to do a good job. But it is about messages that are being sent out that are seen to be the wrong messages, or to be spin. People look at it and say, 'If they spin things do we get the truth?' It's very dangerous territory if the trust isn't there . . ."
This mismatch in trust has serious implications for tackling terrorism. Stevens says he was worried by the reaction to the deployment of tanks to Heathrow airport in February last year. The assumption by many, he admits, was that it was government spin to divert attention from its other problems. That response provided a "very important lesson. If politicians take a decision to put in an extra ring of steel, or take steps that disrupt a terrorist attack, then if people don't believe the politicians . . . we the police have to ensure that the right message is given." Or, to put it more bluntly: "If they don't trust the politicians, then the police have to take the lead on that." Stevens points out that in the past, during other terrorist alerts, the police made announcements of exercises, and suggests that all future operations should revert to past procedure. "That's why the police must never, ever be influenced by political control or be a political football. If we do that, we've lost one of the core golden threads of policing in this country. If we are seen to be manipulated in any shape or form, we are in real trouble." So what exactly did the Heathrow operation achieve? Did the Met really foil something? "Yes, absolutely." An attack on that day? "No, not on that very day, but we certainly did enough to disrupt something, yes."
Stevens, who was chastised by some for saying that a terrorist attack was inevitable, says the threat is "as high as it's been. We're still working as hard as we can, covertly and overtly. The really important thing is to make sure that we don't overreact to what is a very real threat." He says several potential attacks have already been foiled, partly through information provided from within communities. "We know we've stopped attacks taking place in London. We've either disrupted them or arrested people." Scotland Yard used to get 20 calls each day; now the total is up to 200 and some of them are "very helpful to what we do and what we know".
We get on to Iraq. I ask him if he is comfortable with everything that has happened. He pauses and offers: "I don't think it's for me to give an opinion on that," which, as many in the force would testify, is hardly a ringing endorsement. "The war has inflamed passions, but it's our job to ensure that we calm things down," he says, adding that "our relationship with the Muslim community, at the borough-based level, is outstanding". He makes a broader point about motivation. "We've got to be very careful of terrorism and disenfranchisement. If people don't feel part of the community they're living in, and get disenchanted and angry with it for all sorts of reasons, then that will encourage people to become fundamentalists or to want to strike out against society."
He makes clear, however, that he does not believe Tony Blair allowed Iraq to divert attention from the domestic threat. "I go to events chaired by the Prime Minister, and the thing that's always impressed me is that the first people he asks for an opinion are the professional services, and certainly the police. He will listen to what that professional opinion is."
Stevens has no regrets about the dozen people who are being held at Belmarsh high-security prison without charge. He defends the provisions of the Terrorism Act 2000, saying they have "been proven to be effective . . . the powers that have been brought in with the act, with the safeguards, are absolutely what we need. David Blunkett, the government, and parliament which passed it should be complimented." He insists that preventive detention "in the right circumstances is absolutely essential".
What of those other prison numbers - the record number of 75,000 people currently held in jail in the UK? "We're arresting more people than we've ever done before, and one of our problems is that we don't have enough cell space to put all the prisoners in there. Of course the prison population has reached saturation point." He accepts that the number of people locked up is hardly a barometer of success of either policing or the criminal justice system. "But we will not stop arresting people just because of that . . . It's our duty to arrest people who breach the law. We want to be as efficient as possible. That means locking up as many people as possible who commit offences and whom the courts decide to put in prison." He concludes: "I'm afraid my job is to make sure that prisons are full." But he also says: "I do believe there are other ways of dealing with the people."
Stevens made clear his misgivings about Blunkett's battle with Humberside Police Authority over the Home Secretary's decision to suspend the area's chief constable, David Westwood, following the Bichard inquiry into the Soham murders. Stevens points out that the appeals process for Westwood could last up to three years. "No one will end up being in credit," he says. "I'd rather have seen a matter like that dealt with in a way that allows everyone to come out with dignity, and for it to be done in a way that was for the benefit of policing in that area." He makes a more general point: "I'm on the record as saying local problems are best dealt with locally." The fashionable phrase is "ward-based policing". He talks of a "local contract with local people".
I ask him about the challenges facing his successor. He points to three - terrorism, alcohol-related violence and a better ethnic balance in the force. For every issue, he has statistics pouring out of his head. At present, fewer than 7 per cent of the Met's employees are from ethnic minorities. If it were reflective of the population at large, that should be 30 per cent. The fastest-growing problem, he says, is drunkenness. Roughly 48 per cent (another stat) of the most serious crimes, including grievous bodily harm and rape, are related to drink. "We've got a problem in this country of binge drinking. People are acting in a way that is completely outrageous." It is, he says, "the growing social problem" of our time.