The increasing numbers of A grades awarded at A-level are largely dominated by independent and selective schools, according to an analysis presented by the exam boards, which suggests a stark north-south divide in academic achievement.
Yesterday's A-level results saw a record-breaking one in four being awarded an A grade, while the 26th annual increase in the pass rate takes it above 97% for the first time. The results triggered a new row over standards and the problems facing university admissions officers in choosing between straight A candidates. More than one in 10 pupils sitting the exams got three As this year, with a resurgence in pupils studying maths, foreign languages and the sciences. These subjects traditionally attract the brightest students who score higher grades. The gap which has seen girls out perform boys at A grades for several years narrowed slightly.
But there were new concerns about academic standards in state schools. The exam boards published an analysis of six years of results which suggested marked regional differences in the rate of A grades awarded. In the south-east the proportion of A grades has risen to 29.1% of all entries this year, a 6.1 percentage point rise on 2002. In the north-east there has been only a 2.1 percentage point increase to 19.8% of all entries since 2002.
In the same period, independent schools have increased the proportion of A grades they get by 9.1 percentage points compared with a 3.9 percentage point increase in comprehensives. Grammar schools increased their A grades by 8.3 percentage points. A quarter of all A-levels were sat in independent schools despite only 7% of children in England going to one.
Mike Cresswell, of the AQA exam board, said the regional breakdown showed a "long-standing historical pattern" which proved there was no uniform lowering of standards across the system.
John Dunford, general secretary of the Association of School and College Leaders (ASCL) and former head of a north-east secondary school, said: "It reflects the socio-economic problems and low aspirations in places like the north-east. It's part of a wider social story. There are many more independent and selective schools in the southern half of the country than in the north."
Figures collected by the Department for Children, Schools and Families, reveal that in 2007 just 3.2% of children in the north-east are privately educated compared with 11.3% of pupils in the south-east. Asked about the effect of independent schools on the education system, Jim Knight, the schools minister, attacked their use of selection.
"For many independent schools their reason for being is to get their results up, but it's just the result of creaming off the best. By definition if you cream off the best, you will get different results."
But he insisted that state schools had also improved significantly. "There were 75,000 more entries in the maintained sector getting As at A-level."
Student leaders said the research strengthened the arguments for the top universities to take into account applicants' backgrounds, their school and the level of deprivation they grew up in when considering their applications. Wes Streeting, president of the National Union of Students, said; "This makes it more important for universities to take into account contextual information about a student when they apply."
Michael Gove, the shadow education secretary, said: "It is very worrying that there is such a large gap in achievement between different areas of the country. The government is letting down children in the more disadvantaged areas who, as a result, fall behind in school."
Annette Brooke, the Liberal Democrat spokeswoman for education, said: "There is now a clear divide at the heart of our education system. Ministers must work to find the reasons for this inequality and ensure that any improvements in our schools and colleges benefit all students."
Bill Rammell, the higher education minister, said: "We are doing well but we need to do better at ensuring that every school in every part of the country benefits from those improvements."
Knight added: "I think we should celebrate standards improving, just as we would celebrate any Olympic medal." He said the government had set up a series of "City Challenge" programmes to focus support for schools where it is most needed.