Heads are considering legal action against exam boards on the basis that ethnic minority pupils and those from poorer homes are likely to have been disproportionately hit by yesterday's lower than expected English GCSE grades.
The Association of School and College Leaders (ASCL) is backing an investigation started by England's largest academy chain into the backgrounds of pupils denied grades vital to their future lives by exam board decisions.
Brian Lightman, ASCL general secretary, said: "We suspect the very ad hoc decision that was made to lift the grade boundaries has disproportionately affected certain groups of students and so we think it is very worthwhile to examine this further and gather evidence.
"If we are advised that legal action is the right way to challenge this, then that is what we will do."
The Academies Enterprise Trust (AET), which runs 29 academies, is asking schools across the country to send it anonymised information, via the TES, about the backgrounds of pupils who missed out because of the grade boundary decisions on the English GCSE.
Legal action over the controversy has already been mooted by individual schools and local authorities including Bradford and Leeds.
But this is the first suggestion that it could focus on alleged discrimination against the already disadvantaged, an outcome that could be deeply embarrassing for ministers who have pledged to improve the education of such pupils.
David Triggs, AET chief executive, said he wanted to know whether exam boards conducted impact assessments to look at the effect that shifting grade boundaries had on particular groups of pupils.
"They had a duty of care to these pupils so did they conduct these assessments?" he said. "We want to find out whether this has actually affected the very pupils that the government are trying to raise standards for. We want them treated fairly."
The Specialist Schools and Academies Trust is also backing the campaign and operations director Bill Watkins, said: "I do believe that most vulnerable children from the most vulnerable schools are likely to be hit by this [move in grade boundaries]."
Of the 20 AET academies with GCSE cohorts all were affected to some degree, Mr Triggs said. Pupils in AET academies that been entered early in June 2011 or January 2012 for English GCSE had tended to do well, while results dropped for those who had entered pupils this summer.
One school had predicted that 64 per cent of its pupils would achieve English C or above and 70 per cent for maths. The maths prediction was exactly right, but in English it fell massively short at 38 per cent.
In London, NUT leaders are organising a protest against English GCSE results outside the Department for Education on Tuesday. They claim that education secretary Michael Gove "stands behind this disgraceful gerrymandering of results".
*Schools are being asked to send in details of every pupil who they believe should have got a C grade or above and ended up with a D or below in GCSE English because of grade boundaries being raised.
This should be done in spreadsheet form and include pupils' gender, ethnicity, whether they are eligible for free school meals, whether they are higher, lower or middle performers, and the first three digits of their postcodes.
Pupils' names should not be included, but the name of the school and exam board used should be. The AET has checked with the Information Commissioner that sending such information will not break the law so long as pupils are not identified by name. All information will be kept confidential by the AET and TES. Spreadsheets should be emailed to: EnglishGCSE@tes.co.uk