January's GCSE English exams were "graded generously" but the June boundaries were properly set and candidates' work properly graded, Ofqual has said.
In its initial report into this summer's English results, the regulator said it had concluded that when exam boards came to set grade boundaries in June, they were "better equipped to make judgments as there was more information available".
It admitted that the grade boundaries were higher in June than they were in January. Students who gained their English GCSE this summer will be given an extra chance to re-sit, Ofqual said.
Ofqual chief regulator Glenys Stacey said: "We are grateful to schools and colleges for bringing their concerns to our attention so quickly. In response, we have looked carefully at how the exam boards have managed the awarding of all GCSE English qualifications this year.
"People were particularly concerned about the June grade boundaries. We have found that examiners acted properly, and set the boundaries using their best professional judgment, taking into account all of the evidence available to them. The June boundaries have been properly set, and candidates' work properly graded.
"The issue is not the June but the January boundaries. Again, examiners used their best judgment in setting these boundaries, but they had less data and information to work with.
"Most candidates were not sitting at the time, they were waiting for June, and because they were new qualifications, examiners could not rely so much on direct comparisons with the past. As a result, those grade boundaries were set generously.
"We have spoken to exam boards and they have been very responsive. Recognising the strength of feeling, they will be offering early resits for students who sat the June units. We will also talk with schools, exam boards and assessment experts to see what lessons can be learnt and what can be done better in the future."
Ofqual began an investigation into this summer's GCSE English results following an outcry from schools. As national GCSE results were published last week, angry headteachers claimed that exam boards had raised grade boundaries in English halfway through the year amid fears that too many children were going to get a C.
The regulator said that it will not be revisiting the June grade boundaries as they are right and it would contradict its responsibility to maintain standards. Pupils will be given a one-off re-sit chance this November.