Schools in Bradford have joined an alliance to demand an independent inquiry into the GCSE English grading fiasco.

The Bradford Partnership, an organisation made up of 24 secondary schools in and around the city of Bradford, has joined the alliance, which said it has “lost confidence” in Ofqual and does not feel the exams regulator should lead an investigation into itself.

The move comes following continued concern that thousands of pupils were unfairly penalised by the altering of grade boundaries in GCSE English between January and June.

The unprecedented alliance, made up of schools, Academies and teaching unions, has begun a petition calling for the issue to be debated in Parliament.

Bradford Partnership chief executive Nick Weller, executive principal of Dixons’ Academies, said: “Students have not been awarded grades fairly this year and, for some, this will have a significant impact on the opportunities available to them now.

“It’s not fair on them and Ofqual have to do something about it. We want an independent inquiry into what went wrong this year.”

Mr Weller described the English results as “perverse” and “inconsistent” and said students who would have got a C in any other year had been awarded a D, if they sat certain papers in June.

He said: “Students have lost apprenticeships this year because of this. They have found it more difficult to get on their A-level courses and some of them, in two years’ time, will find it also affects university applications or makes it difficult to get into the university they want to, if this isn’t put right.”

Mr Weller said schools in the district had doubled the rate of progress in its national measure of five A* to C grades including English and maths since the partnership formed a year ago.

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”.

Brian Lightman, general secretary of the Association of School and College Leaders, said: “The row is about fairness. It is wrong for pupils to be graded differently for the same exam.”

An Ofqual spokesman said: “We want to fully understand the concerns being raised by teachers, headteachers 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.”