Bright children from non-academic homes achieve more in selective or independent schools than their equally able counterparts at comprehensives - if they stay the course.
New research reveals that though success is more likely, working-class children are also at greater risk of dropping out at 16 than those who stayed at their local comprehensives.
The conclusions of a study of the Assisted Places Scheme may cause ministers to doubt the wisdom of phasing out state-subsidised places in independent schools. It suggests that potential high-flyers who do not have university-educated parents have greater difficulty realising their potential in comprehensives than in private schools.
The research - by Geoff Whitty of London's Institute of Education, Sally Power of Bristol University and Tony Edwards of Newcastle-upon-Tyne - compared the career success of bright students from across the sectors. It is unlikely to be welcomed by a Government committed to comprehensive education.
In the main, children who win an assisted place at private schools go on to the more elite universities and end up in higher-paid professional jobs.
The study looked at the careers of 347 pupils at school in the 1980s who at the age of 11 had been identified as potential high-flyers. Overall, the study suggests that most achieved their potential whether they went to an independent school, a grammar or a comprehensive.
However, the mean score at A-level for those who attended an independent was 23.1, compared with 17.6 points in the state sector (16.5 with grammar school students excluded).
Students who had attended independent schools were more than twice as likely to go to elite universities as those who had attended a state school.
Those from the independents were more likely to have studied traditional subjects and their degree choices were more likely to be skewed towards medicine and law.
However, one of the significant findings is that the A-level performance and university destination of assisted-place holders was closer to that of their fee-paying classmates than to those of students in comprehensives.
But Martin Roberts, head of Cherwell School, in Oxford, who broadly agrees with the findings, believes that access to elite universities, is hampered not by pupils' intelligence but by external factors: "I have been talking about the need for greater access to Oxford and Cambridge for many years but, we are not on a level playing field - private schools are geared to Oxbridge."
A possible further reason for the discrepancies is voiced by Bernie Trafford, the head of the independent Wolverhampton Grammar School: "The state sector is stretched because it is underfunded, which makes it even more difficult to concentrate resources on academically able pupils."
Earlier research by Professors Edwards and Whitty has shown that very few working-class children take up assisted places. They note in this study that four of 12 assisted-place-holders from manual backgrounds left school at 16, compared to five of the 32 with similar academic potential that went to state schools.
According to Professor Whitty, the research suggests non-selective schools may need to pay more attention to the needs of academically able students.
Any wholesale return to selection was not likely to be on the cards. "It may that the existence of selection reduces the critical mass of able children in non-selective schools," said Professor Whitty.
Destined for Success? Educational biographies of academically able pupils, was funded by the ESRC. Further details from Anne Pinney on 0171 612 6459.
* Case study: Tom - embarrassed by home
Tom's working-class background did not hamper him from achieving 12 O-levels and three grade As at A-level as a boarder on an assisted place and an academic scholarship.
At school he said he felt "embarrassed" by his home and was unable to take his friends there because "it was too small". He said he "lacked confidence", which he gained when he went on to Bristol University.
Conversely, Tom never identified with public school, seeing it as the preserve of those who "like to boast about their status".
Tom's older brother, Jake, left school at 16 and is now a printer. Tom said he found it an "odd situation" that his brother stayed at home while he left - and is still there.
Tom achieved a 2:1 in engineering and electrical engineering and now works as a software engineer. He has no intention of educating his own children privately.
* Case study: Ann - OK at school, but teased
Ann's parents divorced when she was seven years old, but her mother worked full-time to finance a private primary school for both Ann and her sister, Jane.
There is no family background of private education, but Ann went on an assisted place to a private high school for girls where she achieved nine O -levels, and four grade As at A-level.
She said she felt "OK" at school, despite being teased about her exam results. She eschewed Oxbridge, opting for Bristol University where she studied electrical engineering.
She said she felt "out of place" at Bristol, which she described as "very public school and affluent", while she felt relatively poor.
Upon graduating with a 2:1, Ann was taken on by a firm of accountants in London where she holds a senior position with a correspondingly high salary. However, she feels her North of England accent could still be an impediment to progress.
* Case study: Pam - no regrets about her comprehensive
Pam describes herself as "proudly working-class" and is very positive about her comprehensive school, where she was head girl.
She said that she did well there "on account of hard work and diligence" and added that her three Bs at A-level were " a great surprise".
She was aware of other schools and felt antipathy towards the local girls' private school which she described as "too snobby and too middle-class".
She felt that she would not have fitted in socially and was concerned that the school would have pushed her too hard academically.
Both of her parents recognised the need for Pam to do well at school, despite neither of them having achieved academic success themselves.
Pam went on to Roehampton Institute of Higher Education where she achieved a 2:1, and she is now a primary school teacher, a job she has wanted since she was seven.
Her one regret is the lack of careers guidance in her education which prevented her considering any other career possibilities outside teaching.