More than 45,000 students are to resit their English GCSEs next month after complaining they had been downgraded.
Figures from exam boards show about one in 14 of those who took the exam earlier this year will take the paper again.
The move follows a row about grades this summer. But what is the dispute about, and who will be affected? Find out with our simple Q&A.
The basics
The move to allow pupils to resit their papers follows the shifting of English GCSE grade boundaries which left thousands of pupils with lower grades than expected.
Many pupils who had been expecting a crucial C grade were given a D as a result of the grade boundary changes. This means many will miss out on college places.
Head teachers urged England's exams regulator Ofqual to investigate when it was revealed that grade boundaries for the exams changed between January and June.
Heads claim those who sat the exam in June were put at an unfair disadvantage over those who sat them earlier in the year.
Exam boards told reporters grade boundaries had changed significantly mid-way through the year. Alterations were as much as 10 marks.
Anger intensified when Ofqual refused to order exam boards to regrade the English GCSE.
It acknowledged grade boundaries had changed part way through the year, but stood by the new June grading system.
Instead of regrading, pupils would be offered early resits in November, Ofqual said.
While it has refused a regrade, it is investigating the quality of exam marking, following complaints about the unreliability of some results.
Who will retake?
Pupils from England, Wales and Northern Ireland have been offered the chance to redo part or all of their GCSE English.
Figures from four exam boards, AQA, Edexcel, OCR and WJEC, show more than 45,000 candidates have opted to take part in the November resit.
Of these, the majority - around 32,000 - are candidates with the AQA board. This is because AQA has a high number of GCSE English students, with 380,000 sitting the qualification in the summer.
Both OCR and Edexcel each have around 4,300 candidates taking part in the resit, and WJEC, the Welsh exam board, has around 4,700.
Exam boards are offering the English resits free of charge to schools.
However, head teachers have warned thousands of London teenagers will miss out on the chance to re-sit their English GCSEs, the Evening Standard reports.
Pupils who have left school, started work or moved house will miss out, and children from schools that do not have sixth forms will be the hardest hit, heads claim.
Is everyone happy with the retake plan?
No. Head teachers say pupils who were affected should not have to resit, as the problems were not their fault. They are calling for this summer's GCSE English papers to be re-graded.
Local authorities, teaching unions and schools have begun a legal challenge against exams regulator Ofqual's refusal to re-grade the papers in England.
In an unprecedented move, they have written formally to Ofqual and exam boards AQA and Edexcel, threatening to seek a judicial review.
As of today the alliance is pressing for June's papers to be regraded in line with the January C-grade boundaries.
In its pre-action letter, the alliance said pupils who took GCSE English in June had been treated with "conspicuous unfairness", BBC News reports.
A spokesman for the alliance said that following a meeting of legal representatives on Wednesday, it had been decided a claim for a judicial review will be put forward next week.
Brian Lightman, general secretary of the Association of School and College Leaders (ASCL), maintains: "We've said all along this is not the solution, because if the exams are graded in the same way as they were in the summer then students will still find their results are down.
"What this shows is that it is a gross injustice that this vast number of students are being subjected to go through a resit when the fact is this is not their fault."
Last month a GCSE English moderator of 16 years resigned over the shifting of English GCSE grade boundaries.
In his resignation letter Mr McKenzie said the grade boundary shift was "the worst decision ever made by AQA".
What has happened elsewhere?
In Wales, Education Minister Leighton Andrews ordered the WJEC exam board to regrade Welsh students' English papers.
As a result, nearly 2,400 Welsh pupils who took English with the exam board received better results, BBC News reports.
