While the league tables have been frequently criticised by schools from deprived areas, the 600-year-old public school is now saying that the league table positions are "absolute nonsense".

According to official figures published in the league tables this week, 39% of pupils at Winchester College achieved five or more good GCSEs, a performance that compares with its score of 92% last year.

International GCSEs are not included in school league table scores

In the national league, this means that the prestigious Hampshire school is level pegging with Dinnington Comprehensive School in Rotherham and Whitefield Fishponds Community School in Bristol.

The reason for the sudden fall is the school's adoption of International GCSEs (IGCSEs), rather than the conventional GCSE qualification.

Even though the international exam is set by the same exam board as the mainstream qualification and is judged by examiners to be of an identical level of difficulty, the IGCSE is not counted as an exam pass in the league tables.

Winchester College's under-master, Phillip Williams, says that this year 100% of pupils achieved five or more GCSEs and IGCSEs - but only the GCSEs were counted for the league tables, producing an apparent pass rate of 39%.

Despite the "ridiculous" league table ranking, the college is planning to move even more of the school's exams to the IGCSEs, which Mr Williams forecasts will mean a league table score of only 29% next year.

The examining board, the University of Cambridge Local Examinations Syndicate (UCLES), says that the international qualification, which is taken by tens of thousands of pupils worldwide, does not come under the regulatory authority of the Department for Education and as such is not included in the league tables.