By contrast, Hills Road Sixth Form College in Cambridge is 25 years old, charges its students nothing and takes pupils who average C grades in their GCSEs. Yet each year this state school notches up A-level results that many an independent school would be proud of.
This year it had a points score of 28.7 per pupil, the equivalent of more than two As and a B for each of its 660 students, although this includes general studies, which is taken by all Hills Road's students and which pushes up a school's score. At Eton, where only 28 of the 264 students took general studies, the points score was 29.4. Winchester students do not take general studies.
Margaret Ingram, deputy principal at Hills Road, said: "We have a great deal of commitment from staff and students. Everybody comments on the ethos here. There's a vibrancy about the place which is quite natural - it comes from well- motivated students.
"We are in a community where everyone is working towards the same goal. Ninety per cent of our students go on to higher education. Of course, that also means that the staff have got specialist knowledge of their subjects and teaching it at A-level."
James Sabben-Clare, head of Winchester, said: "What we are aiming to do is to provide the best possible all-round education for these selected boys. If you bring together the resources and create the environment then exam success is going to follow. Exam success is incidental to the provision of an all-round education."
A-level results for top independent schools improved sharply this year, according to the provisional figures published here, which do not include general studies.
The figures show that 34.8 per cent of independent school A-level entries were awarded grade A, up from 33.5 per cent last year. This is twice the 17.5 per cent recorded for all the schools in the country.
The figures are hardly surprising, given that the schools at the top of the independent school table are highly selective, admitting pupils only by competitive examination. By contrast, most state schools are comprehensive and take pupils of all abilities.
Although the celebrated public schools dominate the top of the Isis table, the full league gives results for 515 schools, with an average of 33.137 candidates: these are mainly local independent day schools, which compete closely at the grass roots with state comprehensive counterparts.
They are by no means all stratospheric performers. Some 212 of the Isis schoolsgained fewer than 20 A-level points per candidate - equivalent to grades of B, C and C.
t Sevenoaks School is included in the table, although many of its pupils take the International Baccalaureate. Its results are converted to A-level points scores. Hurst Lodge School in Ascot, Berkshire, has been omitted because it had only one entrant, who scored 32 points.
A Class Apart: pounds 12,000-A-Year Public School v State Comprehensive
WINCHESTER COLLEGE, HAMPSHIRE
Age: Founded in 1382 by William Wykeham, Bishop of Winchester.
How many students: 678 (134 took A-levels this year).
Costs: Day pupils pounds 11,709 a year; boarding pounds 15,345.
Subjects: 20 at A-level. Students do not take General Studies.
Buildings: Fourteenth-century hall, 17th-century schoolroom. Excellent art, music, drama facilities.
Selection policy: Highly selective - the majority of boys in the top 10 per cent of the ability range. Entry is by the school's three-day entrance exam.
A-level results: Average points score per candidate 34.1 (equivalent to more than three As).
HILLS ROAD SIXTH FORM COLLEGE, CAMBRIDGE
Age: 100 years (as high school for boys); 25 as a specialist sixth form college.
Number of students: 1,500 (660 took A-levels this year).
Costs: Free (No endowments; annual budget pounds 2,900 per head).
Subjects: 43 at A-level and AS-level, two at advanced GNVQ. All of the students take General Studies.
Buildings: Five-acre site with buildings dating from 1900 to the present day.
Selection policy: Heavily oversubscribed, but describes intake as "comprehensive".
A-level results: Average points score per candidate of 28.7 (equivalent to AAB).