The country’s leading exam boards are ‘estimating’ hundreds of A-level grades every year in cases where papers have ‘gone missing’, it has been revealed.

Speaking with The Telegraph, chief executive of the Oxford Cambridge and RSA (OCR) board – the UK’s leading awarding body for providing A-level, GCSE, and vocational qualifications at over 13,000 centres – admitted how the board is forced to estimate grades after papers either get lost in the post or are put into wrong envelopes.

Mark Dawe added how the practice happens every year in schools and said the board does not want to “punish the child for an administrative error.”

The admission has come just days before thousands of students from across the country will be receiving their exam results which will determine which university they will get into.

Mr Dawe said: “It might be the school, it could be us. We have so many processes in place.”

He went on to reveal how, if there is enough material on-hand to award a grade, the OCR will do so – but said the board will not do it for large numbers of pupils and that there has to be a valid excuse in place.

It is understood the policy was brought into place to avoid students from having to re-sit their papers.

Describing the practice as “disturbing,” Peter Hamilton, of the Headmasters’ and Headmistresses’ Conference, said pressures on exam boards – following constant changes by the Government to course regulations and timing of exams – has made accurate and timely marking difficult to manage.

He added how it is challenging to recruit “sufficient, high-quality examiners” and warned how young peoples’ life chances are being tainted by the practice because they are so reliant on accurate grades to be issued at the right time to get into top universities.

The confession has come following a crisis in confidence over exam-marking after appeals against A-level and GCSE results reached a record 450,000 last year alone.

This figure was an increase of almost 50 per cent in 12 months and the number of grades-changed was around 45,500.