Schools, academies and teaching unions have announced they have formed an alliance to demand an independent inquiry into the GCSE English grading fiasco.
The group said it has "lost confidence" in Ofqual and does not feel the exams regulator should lead an investigation into itself. It has also launched a petition calling for the issue to be debated in Parliament.
The action comes amid continuing concern that thousands of pupils were unfairly penalised by the altering of grade boundaries in GCSE English between January and June.
As the unprecedented alliance was announced, a survey found that many parents believe the Government should order an independent investigation.
The poll of 1,000 parents, commissioned by the Times Educational Supplement, found that almost half (48.9%) believed ministers should sanction an investigation immediately, while 26.2% were against it. The rest were unsure. Almost a third of parents (31%) were unhappy about the GCSE grading crisis, while 22.7% were happy. The remainder were not aware of the situation or neither unhappy or happy.
The alliance, which includes private and state school groups, said the decision to band together showed the "strength of feeling against a transparently unjust procedure that grades students inconsistently for the same exam".
They argue that the grading changes will have "massive implications" for schools and pupils, with students left in limbo over sixth form places, or at risk of losing out on apprenticeships. It could also damage students' university chances as many institutions ask for a C in GCSE English, regardless of A-level results.
Brian Lightman, general secretary of the Association of School and College Leaders (ASCL), said: "The row is essentially about fairness. It is wrong for pupils to be graded differently for the same exam. Schools have not complained about the results in science - which dropped nationally by an even larger amount than English - because that process was seen as fair and transparent."
The organisations joining the alliance are ASCL, the National Association of Head Teachers, the Headmasters' and Headmistresses Conference, the National Union of Teachers, the Girls' Schools Association, the Specialist Schools and Academies Trust, the Association of Directors of Children's Services, the Association of Teachers and Lecturers, the Academies Enterprise Trust, the Independent Academies Association, the National Association for the Teaching of English, and the Bradford Partnership.
An Ofqual spokeswoman said: "We want to fully understand the concerns being raised by teachers, head teachers and their organisations about GCSE English. That is why we have been working hard over the past few days to meet many of them, listen to their views and share evidence. Their views and evidence will inform our thinking and investigations as we continue our work."