He’s different – but now Stephenson must really change the Met

Perhaps the most important word in that last sentence is "may". On Sir Paul's second day, it would be wrong and foolish to dismiss the possibility that he can bring about the change the Met so transparently needs. But if he does not do so, he will fail; and there are real grounds for fearing that he will not do so.

These have been terrible years for Britain's largest force, and Sir Paul was at or near the heart of much that has gone wrong. Until recently, his main public role was as chief human shield for Sir Ian, whom he described after the famous bugging-of-the-Attorney-General episode as "the right man to lead British policing".

It was Sir Paul who defended the conduct of officers during the de Menezes shooting, and the decision to allow a Muslim PC to opt out of guarding the Israeli embassy. It was he who described the 2006 "airliner plotters" as planning to cause "mass murder on an unimaginable scale" by downing aircraft, a description which complicated things in court when the evidence for the airliner part of the plot proved somewhat thin and was rejected by the jury.

Sir Paul, by all accounts, was among the very last of the Met's top leaders to lose confidence in Blair, and it is he who has been in effective operational charge of the force for far longer than the four or so months since Sir Ian's resignation.

The Met's problems, if anything, worsened after that happy event: it was, of course, Sir Paul who approved the infamous raid on Parliament and the detention of a Tory frontbencher, an action showing not just indifference to democratic principles but a terrible lack of political nous.

The Met's defenders will point to the recent falls in London crime. But that actually underlines the difficulty. If you're cutting offending but the public still doesn't believe it or feel safer, it suggests that the real problem isn't simply crime at all - it's policing.

Nearly all the Met's greatest crises of the past four years have been caused not by its traditional enemies - politicians, bean-counters, terrorists, rioters - but by itself, and specifically by astounding failures of leadership. Jean-Charles de Menezes was not, as some have said, the 53rd victim of the London bombings; he was the victim of police incompetence.

Incompetence primarily on the part of the operational leaders on the day and by the Met's top leaders in the years before and after the shooting. They failed to foresee the situation that arose, failed to draft robust enough rules for killing someone on mere suspicion. Then they made things infinitely worse by trying to block an investigation, refusing to admit their mistakes and continuing to smear and victimise the dead man.

Last week a furious 2007 letter from Sir Ian Blair to Boris - attacking his description of the Stockwell firearms squad as "trigger-happy" - was published by Channel 4 News. I have a feeling that the letter's real intended audience was not Boris, but the then head of the squad, to whom it is copied.

Sir Ian must have known that his outrage was unjustified. "Trigger-happy" is a perfectly fair description of the Met firearms squad: they do kill more of their targets, proportionately, than the firearms unit of any other force. Around the time the letter was written, however, the squad was reportedly threatening to down tools - and leave London unprotected from armed criminals - if this inconvenient fact was made too much of, or if any of its members were disciplined or criticised over de Menezes. And so none ever were.

A failure to tackle - indeed, a willingness to defend - the Met's vested interests explains a lot of the dissatisfaction ordinary Londoners have with the police. A minority of officers, including some at high levels, do not understand that they work for our benefit, not their own. This, too, has been a failure of leadership. And among the Met's topmost leadership throughout it all was Sir Paul Stephenson.

Stephenson is clearly different, politically and personally, from Blair. He will probably connect better with the troops. Let's hope that his public association with the leadership failures of the past spurs him to fundamental change.

His model should be the kind of policing now being tried in Leicestershire and Surrey, increasing individual officers' discretion, dealing with minor matters informally and repudiating Home Office targets, with their premium on easy arrests to bump up your activity numbers. Successful policing cannot always be measured; measurements are sometimes the enemy of successful policing.

But with Kit Malthouse, Boris's deputy for policing, expressing his desire for a "pretty boring" commissioner, it's not clear that fundamental change is what's wanted from City Hall. It should be. Because having finally realised, about a year after everyone else, that Boris is neither the Antichrist nor an idiot, the Mayor's opponents have the first glimmers of a more effective attack line - and that same word, "boring", features in it.

I've always believed that the greatest threat to Boris's re-election is not that he will make some huge blunder but that we will reach 2012 and people will ask: what has he accomplished? What has really changed? What flagship achievement can he point to?

If Boris and Stephenson can rebuild the relationship between police and law-abiding Londoners, that would qualify. If he can put police on the streets in the same numbers we see in New York, that would qualify. That would be change. But the danger, and I do hope he'll prove me wrong, is that Paul Stephenson is to change in British policing what Gordon Brown is to change in British politics.