The university, deemed to be one of the most prestigious in the UK, currently admits more than a third of its students from public schools and has demanding entrance criteria.

But it wants to recruit talent from across the social spectrum, and is launching an "alternative admissions scheme" aimed at selecting promising pupils from schools with poor A level records.

The initiative is based on one already operating in the university's law department.

It means that students who achieve good, but not outstanding, results from schools where A level scores are low will be considered alongside those with top results from high-achieving schools.

Public schools upset

The university, where Prince William is said to be considering reading history of art, says the scheme is about "widening participation".

Oxford University is also trying to "widen access"

This summer, it held its second annual summer school to introduce state school pupils to all aspects of life at university.

The university says the summer schools, which also operate at Oxford, Cambridge and Nottingham universities, are "invaluable" in widening the base of its applicants and indentifying "bright, well-motivated students who may have been educationally disadvantaged".

The summer schools are sponsored by the Sutton Trust, which was founded by businessman and philanthropist Peter Lampl in 1997, with the main objective of providing educational opportunities for academically able young people from non-privileged backgrounds.

But the new admissions policy has upset some representatives of public schools, who believe that high-scoring public school candidates could become victims of positive discrimination and be passed over in favour of state school applicants with lower grades.

University spokesman Don Carleton said: "This is not about positive discrimination, social engineering or dumbing down. What it is about is finding and identifying academic potential.

"A student who happens to be excellent at a subject in an under-achieving schools may have the same academic potential as somebody in one of the best public schools in Britain, but without the libraries, laboratories and devoted staff may not achieve the same A level grades.

Interview procedure

"It's like saying someone in a school with all those facilities is given oxygen before a 100 yard dash, whereas someone from a poor school has weights around their ankles.

"We value A level grades, but they are only one part of the application form. We look at A levels, O levels, academic references and what the individual has to say about themselves.

"All the indications are that a promising student from a poor school does at least as well as students who come in with high A levels, and there is some indication that they do better."

Mr Carleton said that in the selection process, there were usually a number of students who were "must-haves", and others who were "might-haves".

Applicants from the latter group were awarded places after an interview procedure, and the same would apply to those from underprivileged schools scoring lower grades than those from more privileged backgrounds.

'It's about talent'

"Whether they're from Eaton or Harrow, or from some very disadvantaged place, all students have personal requirements. We try to admit individuals here. We're interested in the talent of individuals, and we want to have a transfusion of new excellence coming in."

In practice, the scheme will work by comparing an applicant's A level grades, or predicted grades, with the average grades achieved by their school.

The theory is that a candidate scoring two Bs and one C at a school where the average was two Ds and and E could have at least as much academic potential as one scoring top grades at a school where achieving A and B grades was commonplace.

"It's not positive discrimination, as that would be insulting and we don't do it. It's about getting talented young men and women coming to us whatever their background," Mr Carleton said.

News of the "alternative admissions scheme" follows moves by Oxford and Cambridge University to try to attract more students from the state sector.

In June, a report into widening access into Oxford University suggested that tests of "core intellectual skills" could be fairer to students from state schools, who might underperform in interviews or A levels compared with pupils from independent schools.