'I can't help thinking that had they remained free, the London of today would be a safer place.' 'They' being those community-spirited boys the Kray twins and 'I' - the author of this fatuous speculation - being Mike Reid, comedian and star of EastEnders.

They weren't actually villains1 you see, but proto-vigilantes, ahead of their time in the application of brute force to matters of public order. Not robbing hoods but Robin Hoods, courteous to old ladies and very fond of their dear old mum.

When I hear stuff like this, a detail from John Pearson's chilling book about the Kray brothers' business methods always comes to mind. When Ronnie was about to administer a rebuke to someone who had failed to come up to the twins' high moral standards he would offer his victim a cigarette, pushing it from the pack and holding it close to the man's lips. As his target bent to take it between his lips he would be struck with Ronnie's other hand - he had discovered that it was much easier to break jaws if they were slightly open.

It is difficult to be absolutely certain why minor celebrities such as Patsy Kensit, Barbara Windsor and Roger Daltrey seem so eager to have the Krays returned to our troubled streets - perhaps they just want someone new to be photographed with, or perhaps it's a simple fascination with crime. Few of us are entirely immune from its glamour.

You could hear the effect at work when Chris Patten talked about Labour's 'porkies' at the last election and you can hear it when law- abiding tax clerks refer to the police as 'the filth' or somebody in the office shouts out 'Who's blagged the directory?'

It's crim-speak and it offers the meekest, the mildest, the most irredeemably middle-class of us the chance to come on like an East End player, the sort of geezer2 who can silence a noisy public bar just by walking through the door.

The Sweeney has a lot to answer for here - both in setting in train a genre of crime fiction in which the policemen look rougher than the villains and in infecting Seventies classrooms with underworld argot. At the height of its success, playgrounds sounded like the exercise yard at Wormwood Scrubs as unbroken voices talked of 'topping' each other, 'doing a runner' and how someone was 'well out of order' for 'grassing'3 on another.

There's a simpler explanation, which may well apply to adult life as well. Schools are adversarial communities in which part of the population spends its time trying to get round the laws imposed by the other part. In relation to teachers pupils do form an underworld, one with its own language and code of conduct.

Disobedience, particularly if carried off with flair and boldness, earns a reward of peer-group admiration. Hardly surprising, then, that schoolboys should have adopted an argot which made transgression sound smart and tough.

We don't stop playing cops and robbers when we leave school. Almost all our relationships - between boss and employee, husband and wife, citizen and state - can be translated into terms of law-making and law- breaking. We mostly imagine ourselves as criminals here ('outlaws' is the more romantic term) and crim- speak is a way of asserting that we're not going to come quietly.

Even Poets Laureate aren't immune; when Ted Hughes talked of the poet's 'inner policeman' he didn't have in mind a friendly neighbourhood bobby making sure that the poet's video-recorder didn't get nicked, but an authoritarian presence that should be ignored. In other words, if the poet wanted to be on to a nice little earner he should do a runner whenever the copper appeared.

1 From the Latin villanus, rustic, low-born.

2 Uncertain but Partridge offers the nice speculation that Wellington's soldiers adopted the Basque giza, man, during the Peninsular Wars.

3 From grasshopper, rhyming slang for policeman. Hence police informer.