Study by Sutton Trust shows 3% of schools account for 33% of Oxbridge undergraduates. Zoe Corbyn reports.
An elite 3 per cent of the UK's schools are providing a third of admissions to Oxford and Cambridge universities, according to a study by the Sutton Trust.
The "deeply worrying" figure cannot be attributed to A-level results alone and in future the dominance of the elite minority is likely to increase, the education charity said.
The study - the first detailed analysis of the extent to which a few elite schools dominate admissions at the most prestigious, research-led institutions - calls into question the value of existing programmes that are in place to widen participation.
While the concentration of admissions is most extreme for Oxbridge, a group of 100 mostly fee-paying schools accounts for a sixth of admissions to the UK's leading research universities.
Sir Peter Lampl, chairman of the trust, said: "It is deeply worrying - not to mention a sad waste of talent - that the chances of reaching one of these highly selective universities are significantly greater for those who attend a small number of the country's elite fee-paying schools."
"Where does this leave the vast majority who do not have access to these opportunities?"
The study looked at admission rates between 2002 and 2006 for 3,700 individual schools and colleges on the Universities and Colleges Admissions Service database. It then compared the A-level results the schools attained. It found the top 30 independent schools had nearly twice the number enrolled at Oxbridge as the top 30 grammar schools, despite very similar average A-level scores. The share of students going to Oxbridge from the 30 schools with the best success rates rose by about 2 per cent over the five years.
State-school students may be missing out on "additional attributes" that A levels do not measure, such as a broader education and experience of leadership and teamwork, says the report. Lower aspirations among state-school students and poor career advice are also highlighted.
Sir Peter said the findings did not necessarily mean that initiatives to widen access were failing, and he called on all parties to do more. "I am in no doubt that the situation would be worse had we and others - including the Government and the university sector - not invested in initiatives such as summer schools and outreach programmes over the past decade," he said.
Geoff Parks, director of admissions at Cambridge, said he agreed with most of the report's conclusions: "There is a lot of work still to be done, but progress is being made." A spokeswoman for Oxford said it could not address the inequalities in the school system alone, but that it was working hard "towards raising aspirations and attainment among school students".
The Sutton Trust is to commit an extra £10 million to widening access projects.