This summer, many schools received their English results later than expected because of extra checks introduced by the Qualifications and Curriculum Authority, aimed at improving marking standards.
Last year more than 17,500 14-year-olds were upgraded after marking errors (2 per cent of the cohort). There were nearly 52,200 requests for re-marks last year.
This year many schools have already demanded that their scripts be re-marked.
One Somerset secondary has asked for all of its English papers be reassessed after pupils were awarded up to three levels lower than expected, the equivalent of six years' work.
Several of its pupils achieved level 8 on the English extension paper for th brightest children - equivalent to good GCSE standard - but only scraped through with a level 5 on the main test.
Lorraine Heath, head of English, said she was angry that the marking was so obviously sub-standard.
"I have no confidence in the quality of the marking, nor in the process which recruits
and trains those who do it," she said.
" It is extremely damaging to be at the mercy of people who are clearly not up to the job."
A north Yorkshire head of English said promising pupils had been undervalued.
"All 217 of our papers have been very badly marked," he said. "Some pupils used really sophisticated analysis of language but have not received any credit."
The official evaluation of 1999 tests showed that most headteachers questioned by the QCA were unhappy with the marking of the secondary English tests.