When Ian Blair, deputy commissioner of the Metropolitan Police, talked recently of setting up an “intelligence nexus” with details of children as young as eight at risk of turning to crime, there was fluttering in the liberal dovecotes.

“An extremely worrying step,” said Mark Littlewood, director of human rights group Liberty. The National Union of Teachers voiced “discomfort” at assumptions being made about such young children. And Elizabeth France, the information commissioner, expressed concern over who would have access to such information.

Mr Blair himself concedes the proposal is “pretty revolutionary stuff”. It would involve holding “sensitive information about large numbers of children“in London, many of whom had not yet committed a crime, and probably never would.

But he stressed that the purpose of holding information was to permit co-ordinated intervention by local police, teachers and social workers to stop these children becoming criminals.

The backdrop to the proposal, he says, is a sharp rise in muggings in the capital, much of it by juveniles on juveniles; a new tendency for such violent crimes of violence to be a young person’s point of entry to the criminal justice system, rather than an advanced step along the road.

He was also disturbed by the revelation during the inquiry into the murder of schoolboy Damilola Taylor of “a feeding chain leading to rampant criminality, a mixture of abuse, victimisation and criminality”.

But the problems to which Mr Blair referred are not confined to London, although they are most acute there. And the approach he outlined - of a new emphasis on prevention and sharing information - is not that revolutionary: thoughtful police chiefs outside London have been urging it in less dramatic terms for some time. In fact in some areas, such as Nottingham, it is already happening (see box).

“The proposal is not a register of naughty children,” insists Charles Clark, deputy chief constable of Essex, on a six-month secondment to the Youth Justice Board as director of prevention. “It is local, on a case-by-case basis. There’s been a lot of hype about sensitivity but this is voluntary, positive, supportive.”

The 1998 Crime and Disorder Act allows partners in the new youth offending teams: police, probation, social services, health and education - to share information to prevent crime. Any recording of names is done under careful observance of data protection rules, says Mr Clark.

He and Commander Dave Wakelin of Nottinghamshire police (also on secondment at the board) have been touring the country to look at crime prevention and will produce recommendations by the summer. They look set to back new local panels to identify eight to 13-year-olds at risk of offending.

One feature of these early identification schemes is that help is offered to families rather than individual children. Nothing is done without parents’ permission. Evidence so far suggests the offer of help is eagerly grasped by parents often at the end of their tether.

CRIME FACTS

* 25 per cent of boys and 15 per cent of girls aged between 12 and 17 admit to having committed a crime.

* In 2000 189,000 young people (3.5 per cent) were cautioned or convicted.

* Average age when offending is 13.5 for boys and 14 for girls.

* Pupils who have been excluded from school are twice as likely as their peers to commit a crime.

* 60 per cent of those excluded from school admitted to committing an offence last year.

Of 171 young offenders surveyed by HM Chief Inspector of Prisoners and the Office for Standards in Education

* 84 per cent had been excluded

* 86 per cent had truanted

* 52 per cent had left school at 14 or younger

* 29 per cent had left school at 13 or younger

* 73 per cent said they had no educational achievements.

Factors associated with youth crime are:

* Drug use

* Disaffection from school

* Hanging around in public places

* Delinquent friends or acquaintances

* Poor parental supervision

* Persistent truanting.