More than 65,000 teenagers may have missed out on C grade passes in their English GCSE because of last-minute changes to grade boundaries, according to the latest analysis of the figures.
The analysis, for the Association of School and College Leaders, indicates at least half of the 133,906 candidates who obtained D grades would have received C if the grade boundary had not been raised at the last minute. David Blow, headteacher of Ashcombe School, Dorking, Surrey – a member of the association's data group – told the Times Educational Supplement earlier calculations that the figure was around 10,000 appeared to be an underestimate.
He said he was basing his analysis on statistics supplied by the AQA (Assessment and Qualifications Alliance) exam board, which had the largest number of GCSE English and English language entries.
The analysis showed pupils who scraped a C in a test on understanding texts and creative writing in January would have needed four extra marks to do so in June. In the higher level English exam, a pupil with a minimum C grade mark in January would have needed an extra six marks in June.
Brian Lightman, general secretary of ASCL, said the changes could have a "devastating effect" on the life chances of pupils who would be unable to take up sixth-form or college places as a result of not obtaining a C grade pass. In addition, schools may be forced to close or become academies as a result of failing to reach a stiff new government target of getting 40 per cent of their pupils to obtain five A* to C grade passes including maths and English.
An AQA spokeswoman said it was a "normal feature of the assessment process" for grade boundaries to change between exam series. Ofqual, the exams regulator, which is conducting an investigation into how the grade boundaries were arrived at, is expected to make a public statement on its progress on Friday.
Both it and Education Secretary Michael Gove called before the examinations for an end to grade inflation and the "dumbing down" of exams. Teachers' organisations say political pressure may have caused the drop in A* to C grades this year for the first time in the exam's 24-year history.