Researchers also state that a grammar school education does not appear to have increased working class pupils’ chances of getting a degree.
The study is based on the education histories of more than 7,700 people in England and Wales who are being followed by the 1970 British Cohort Study.
It finds that pupils who attended private secondary school during the 1980s were around one-and-a-half-times more likely to graduate from a mainstream university than both grammar and comprehensive students with the same A level results.
Furthermore, they were two-and-a-half times more likely to get a degree from a Russell Group university.
The statistics show that, overall, 16 per cent of the people included in the analysis graduated from mainstream universities, while seven per cent gained degrees from either the 24 Russell Group institutions or two other highly selective universities – Bath and St Andrews.
Within these figures, 31 per cent of private school pupils obtained a degree from an elite university, compared to 13 per cent from grammar schools,
five per cent from comprehensives, and two per cent from secondary moderns.
However, the researchers conclude that the apparent success of grammar schools can be attributed to “pupils’ social backgrounds and other factors such as their attainment at age 11”.
“It was surprising that grammar schooling was not linked to any significant advantage in getting a degree,” said Professor Alice Sullivan, the study’s lead author.
“Our preliminary investigations suggest that grammar schools did make a difference at O level, but this did not follow through to university chances. There appears to have been a ‘leaky pipe’ between grammar school attainment and university entrance.
“We also investigated whether grammar schools were especially beneficial for working class pupils who attended them, even if there was no overall grammar school advantage. But we found no statistical evidence to support this argument.”
The research identified two factors that it suggests could account for the greater proportion of former private school pupils with Russell Group degrees.
Prof Sullivan explained: “Higher levels of aspiration in the private sector – both the parents’ and the schools’ – may provide part of the explanation. Then there are the links between the universities and the private schools.”
Having a parent with a degree was also significant, the research found. A person born in 1970 who had at least one graduate parent was more than twice as likely to obtain a degree from a Russell Group university as a pupil with the same A level results, but whose parents had no qualifications.
Fifty-two per cent of privately educated pupils had at least one graduate parent, compared to
31 per cent from grammar schools, 14 per cent from comprehensives, and eight per cent from secondary moderns.
The study will be published by the Oxford Review of Education next month.