The GCSE English grading fiasco has had a "serious impact on perceptions of fairness", Ofqual admitted.
The exams regulator said it recognised the significance of the issues faced this summer, and the impact of the "generous" results awarded earlier this year.
In a written submission to MPs, Ofqual also said that nobody could have seen that January's results were too generous, and that all the evidence pointed towards decisions being harsh. And it insisted that there has been no political interference in the exams.
The submission, sent to the Commons education select committee ahead of the evidence session, sets out Ofqual's investigation so far into this summer's GCSE English grading crisis.
It says that, in general, the awarding of modular GCSEs - in which pupils sit exams and submit coursework over a two-year period - has been successful. But this was not the case with new modular English GCSEs, which were awarded for the first time this year.
"We recognise the significance of the issues with GCSE English this summer: the generosity of the awards in assessments taken before June 2012 has had a serious impact on perceptions of fairness at qualification level," Ofqual said. "If we were not already planning to remove modular GCSEs after the current school year, we think there would now be a strong case for doing so."
Overall English GCSE results at grade C and above were down by 1.5 percentage points this year - in line with predictions.
But Ofqual adds: "There has been an unusual distribution pattern, a greater variation between schools than expected. And for some schools the results are a far cry from their expectations."
The report says it is important to note that "there has been no political interference". And it insists that the regulator played its "proper role, regulating standards".
"Awarding in January and before was generous, but neither exam boards nor the regulators could have seen it at the time. All the evidence at the time was that awarding decisions were if anything harsh."