Most of the controlled assessment work was submitted in the summer and when examiners saw evidence of over-marking, exam boards raised grade boundaries, leading some pupils to receive poorer grades than expected.

BBC: GCSE English: Teachers' anger over generous marking claim

Speaking to the BBC after his meeting with the watchdog, Brian Lightman, general secretary of ASCL, said the issue was not re-marking papers, but altering grade boundaries and "putting right what's happened".

BBC: Heads call for regrading of English GCSEs

In its own report into the controversy, published on 2 November, Ofqual concluded that pressure on schools in England to hit targets led to overgenerous marking of coursework by teachers and that, as a result, external examiners had to raise grade boundaries in the June exams.

BBC: Heads challenge Ofqual to publish all GCSE grade research