The school fell from sixth place last year to 24th this year in the Financial Times' FT-500 list of the UK's top 500 private schools.

The newspaper blamed the plunge on 'unremarkable' A level results at the school, which is attended by Princes William and Harry and charges almost £5,000 a term.

Prince William: Will sit his A levels next year

The drop in the FT table echoes the official league table of A level results in private schools, compiled by the Independent Schools Information Service (Isis).

In the Isis league, Eton came 20th with 28.4 points - roughly two As and a B per A level pupil.

This compares with the top three Isis schools, Winchester, St Paul's and Westminster, which gained 34.1, 32.8 and 32.7 respectively - well over three A grades per pupil.

No 'malaise' at school

However, Eton said it was pleased with its A level results and rejected suggestions that the results pointed to a "malaise" at the school.

Harry has been at the school for one year

Headmaster John Lewis said that about 80 of its 264 A level pupils had won offers from Oxford and Cambridge universities - its highest tally for five years.

He blamed the plunge on the fact that the school's A-level students had chosen, individually, to take fewer subjects. The number of points gained by each pupil, and therefore its league position, was thus "almost certain to be down", he said.

And one educational expert was also buoyant about the results.

Alan Smithers, professor of education at Liverpool University, said demand for Eton places would remain high.

"Eton can probably afford to be fairly blase about the league table," he said.

"Parents choose the school as much for the people their children are likely to meet as for the qualifications they get at the end."