Pupils whose GCSE English coursework was accurately assessed have been unfairly penalised by the “overmarking” alleged to be at the heart of this year’s grading fiasco, according to Ofqual’s chief regulator.

Glenys Stacey made the comments as three out of the four exam boards involved in the controversy contradicted the watchdog’s final report on the crisis, revealing that overmarking was not a reason for them raising grade boundaries between January and June.

It also emerged this week that a legal challenge against the grading by an alliance of schools, pupils and councils would be heard by the High Court in the near future.

Speaking to TES, Ms Stacey conceded that pupils whose English controlled assessment was accurately marked by teachers this summer may have been awarded lower grades than they deserved because of overmarking in other schools. In her report, published last week, she said overmarking was the reason grade boundaries had been toughened up.

“Are there students (who) really suffered because of overmarking - if you like - in other schools?” she said. “One can assume that there are and that is the distressing thing.”

Earlier this year Ms Stacey angered schools by stating that pupils whose work was marked in January - before grade boundaries were shifted - had been the beneficiaries of “generous” marking and had got a “lucky break”. She has not previously suggested that there were any problems with June’s grade boundaries.

But she said it was not possible to identify pupils who had been unfairly penalised. “We have looked at what we could do to somehow recompense for that and there isn’t an easy way,” she said. “And that is a sober reflection for everybody, isn’t it? It is a cautionary tale, this one. There isn’t any way.”

Brian Lightman, general secretary of the Association of School and College Leaders, said: “Having concluded that pupils have been treated unfairly we now need to know what remedy has been made. It is completely unacceptable for this situation not to be put right.”

Ofqual took the affair in a new direction last Friday when its report asserted that a poorly designed qualification and overgenerous marking by teachers were at the heart of the grading crisis. The watchdog said that “examiners saw overmarking” in June and had to move grade boundaries to compensate for that, although this week it admitted that it had not looked at any of the marked papers.

Its report contains statistics suggesting that teachers did overmark and target marks to where they thought grade boundaries lay. But the only evidence it included that directly linked that overmarking of controlled assessment to the raising of the grade boundaries related to just one of the four exam boards involved: AQA.

This week Ms Stacey insisted that all the boards had raised boundaries in June as a response to overmarking, although she could not point to evidence to back up the claim. But the Edexcel and OCR boards have contradicted her, telling TES that they dealt with any overmarking through moderation and not grading. And WJEC revealed it could not have raised GCSE English grade boundaries during the year in response to teacher overmarking because it only graded controlled assessment in June.

Emails have already shown that Ofqual ordered Edexcel and WJEC to raise boundaries this summer and overrule their examiners’ professional judgements. At the time the watchdog made no mention of overmarking, and it glossed over its involvement in the boundary changes in last week’s report.

Meanwhile Stephen McKenzie, a former AQA GCSE English moderator, warned that the board’s “moderation records” used to support Ofqual’s overmarking claims were “flimsy evidence”. He said they might relate to no more than 6 per cent of a school’s candidates. Mr McKenzie resigned this autumn in protest against the way pupils were downgraded.

An Ofqual spokesman said its conclusions about overmarking were based on interviews with examiners from all four boards, rather than the marking itself.

The story so far

• As many as 1,000 schools have seen the proportion of pupils gaining good grades in GCSE English drop by at least 10 percentage points this year.
• About 45,000 pupils have applied to retake the exam this month, in special resits their schools say they should not have to endure.
• An alliance including 167 pupils, 150 schools, 42 local authorities and six teaching unions has been told that the High Court will consider their legal challenge to the grading in a two-day hearing.
• A TES poll last week found that the crisis had led to 93 per cent of secondary schools losing confidence in Ofqual, with more than half saying they had no confidence at all.

• Original print headline: Students who were not overmarked have suffered, admits Ofqual