Only one crime in 39 leads to a conviction, according to a startling Home Office study.

The research project, which has traced the lives of hundreds of men over half a century, points to a hidden wave of undetected crime.

The men admitted committing hundreds of crimes - yet only 2.5 per cent of them led to convictions.

The study raises fresh questions about the effectiveness of the police and courts at bringing criminals to justice.

Officially, police solve around one in four crimes. But that figure includes only the minority of offences which are reported.

The ambitious Home Office project, dubbed the Cambridge Study, was launched in 1961.

It covered 411 primary school boys from an unnamed 'working class' area of South London, who were all then aged eight or nine.

They have since been interviewed about their criminal behaviour at the ages of 14, 18, 32, and finally at 48, providing unprecedented insights into the likelihood of offending and the pattern of criminal careers which they followed.

The study has revealed that 41 per cent of those surveyed had criminal convictions by the time they turned 50.

But 93 per cent of them admitted committing significant crimes such as burglary, theft, assault, fraud and drug use. And almost half of all offences were carried out by men who were never caught and punished.

Researchers found that for every conviction among the group, they admitted to another 38 offences.

A minority of persistent offenders - around 7 per cent of the total - were responsible for almost half the crimes.

Even among those who had been caught and punished, there was an average of 22 offences for every conviction.

The commonest crime was vandalism, with 70 per cent of the boys admitting offending by the age of 14, and 75 per cent by middle age.

Three-quarters admitted carrying out assault, including more than a third by the age of 14, and one in seven were still committing violent attacks in their 40s.

Across the board fewer than one in three self-confessed criminals had ever been convicted.

Tories claimed the findings showed starkly why many criminals believed they would not get caught.

Shadow Home Affairs Minister Edward Garnier, said: "Detection rates are far too low. It is the fear of being caught rather than being sentenced that affects offenders' intentions about committing crimes."