Some of the country's most famous private schools are challenging exam boards to remark their pupils' GCSE papers after a sharp fall in top grades this year.

The OCR board is under-stood to be remarking English literature papers from high profile institutions including Charterhouse, while the AQA board has received complaints from Haileybury, Uppingham and Rugby. Teachers at the schools were concerned their pupils may have fallen victim to rogue exam markers after far fewer pupils at the schools had received A and A* grades in English literature this year than in previous years' GCSE results.

At Charterhouse, in Godalming, Surrey, 37 per cent of pupils scored these top grades, compared to 69 per cent last year. Matthew Armstrong, head of English at Charterhouse, explained: "It is simply unbelievable that a cohort with a very similar profile to last year's should have achieved such varying results."

A spokeswoman for AQA said marking exams was a "thorough and rigorous process". OCR said they had requests every year.