Early intervention to provide pre-school education and parenting skills can save disadvantaged children from a life of crime, a major long-term study suggests.

Adult criminality can be traced back to poverty, poor upbringing, low intelligence, a convicted parent, and restless or impulsive behaviour at the age of eight, it found. Three-quarters of those from the most difficult backgrounds were still breaking the law at the age of 32.

According to the study’s director, Professor David Farrington, targeted initiatives to help families most at risk will prove cost-effective in the long term. “It is not difficult to identify vulnerable groups at a very early age,” he said. “We also found that one predictor of a long criminal career is to start early. In their teenage years these males are in full flow and it is really difficult to deflect them.”

His conclusions come amid widespread concern about juvenile delinquency and rising crime, and reinforce recent calls for more resources for early-years learning.

Researchers from the Cambridge Institute of Criminology followed the lives of 411 working-class men in inner-city south London from 1961, when they were aged eight or nine. They interviewed them eight times up to the age of 32, and tracked their criminal records to the age of 40. Families and teachers were also interviewed.

Two patterns of criminal behaviour emerged: adolescents, often seeking excitement or thrills, who desisted in their early twenties; and “life course” offenders who started at 10 or 12 and continued.

While the average criminal career lasted seven or eight years and involved between four and five crimes, a high proportion of crime was committed by a small number of chronic offenders.

Six per cent of families accounted for half of all convictions. These tended to be multi-problem families with many children living in poor circumstances. A convicted parent among eight to ten-year-olds was one of the strongest indicators of likely offending in adulthood.

Offending was matched by other deviant or anti-social behaviour. By 18, those with convictions tended to drink heavily, gamble, smoke, and to have had sex with several girls at an early age. Their behaviour was aggressive and compulsive, and hostile to authority.

The study identified several predictors of delinquency: * Nearly two-thirds of eight and ten-year-olds described by teachers as troublesome were convicted by the time they were 32.

* Low IQ, poor school attainment, inadequate parental support, poverty, and impulsiveness or poor concentration were also factors.

While a quarter of all convicted juveniles were still committing crime at 40, those from the most vulnerable backgrounds were more likely to start early and persist.

“If you look at boys from low-income families who are successful in later life, the way out of the ghetto is through school success, which is often linked to high IQ,” Professor Farrington said.

The justice system was a poor deterrent. In court, juveniles often received a conditional discharge for a first offence, which they saw as being “let off”.

Professor Farrington believes the findings highlight the importance of preventative action, and present major implications for public policy.

Pregnant women from the most disadvantaged backgrounds should receive intensive home visits to provide advice on diet, child care and health.

He believes “head start” programmes and pre-school intelligence enrichment initiatives can have a beneficial long-term effect, as can training parents to be “warm but consistent” towards children.

Schools should develop with parents explicit policies to combat bullying, which is also associated with delinquency, and use high-status peers to influence pupils’ attitudes to drug use and other crimes.

He also advocates social skills training for impulsive or aggressive pupils to encourage them to think about the future.

One of the early-learning programmes favoured by Professor Farrington is the HighScope model, developed in the United States and followed by about 125,000 children in Britain.

Its three-step model of “plan, do, review” encourages children to make decisions and then accept responsibility for them. A Home Office study to assess its effectiveness among inner-city children is due to be published later this year.

“Nursery education will not do it alone,” said Serena Johnson, director of HighScope UK. “It has to be part of a programme of social support, but it can make a definite impact on the lives of those children.”

The Cambridge study was welcomed by Sir Claus Moser, founder of the independent National Commission on Education, who has identified nursery education and primary schools as priorities for the next government.

“I am very sympathetic to its conclusions,” Sir Claus said. “I believe in this evidence: it is absolutely in line with what I have been saying.”