Enfield has joined other councils and more than 100 schools in a legal challenge to a regulator’s refusal to re-grade GCSE English papers.

The authority, along with boroughs in Camden, Ealing and Brent, has signed a letter to exam regulator Ofqual threatening to seek a judicial review in a bid to force the re-grading of papers.

Pupils across the borough scored lower grades than expected when boundaries were raised halfway through the year, meaning students who took the exam in January got a higher grade than those who sat them in June and achieved the same mark.

The pre-action letter, signed by six teaching associations and unions, 113 schools and 36 councils sets out the case, labelling the situation “inconceivable”.

Ofqual published its report into the controversy on Tuesday, which concluded that the January exams were “graded generously” and that the June boundaries were “right”, refusing to re-grade the papers.