Exam regulator Ofqual has published provisional data showing that the number of enquiries about results and appeals against results “has increased noticeably this year”.
The data, which follows this summer’s exams, shows that GCSE enquiries increased 56 per cent and A-level enquires were up 34 per cent.
However, grade changes increased by just over one percentage point overall. In the case of GCSEs, grades changed in 18.8 per cent of challenges, compared with 17.7 per cent in the previous year.
For A-levels, 19.6 per cent of challenges led to a regrade, an increase of 0.3 percentage points on the previous year.
“The impact of any wrong marking on students or schools is considerable, and marking mistakes undermine public confidence. Earlier this year we reported that the quality of marking is generally good, but could be improved,” Ofqual said.
“Nevertheless, teachers and the public remain concerned about marking and particularly those rare cases where grades change to a baffling extent.”
Russell Hobby, general secretary of the National Association of Head Teachers, said: “The large increase in papers sent for remarking is a sign of falling confidence in exams following many rapid changes.
“The volume of grade changes is worrying. Not all schools can afford to challenge grades on a routine basis, so this opens up real inequities.
“NAHT welcomes the news that Ofqual is looking into marking – we need to get this area right as a matter of high priority. Politicians also need to plan their changes carefully and patiently in future, so that schools can cope.”
The fall in confidence on exam marking comes after allegations of unfair treatment over GCSE gradings in 2012, when Ofqual faced legal action from local authorities and teachers after the number of A*-C grades fell for the first time in 24 years.
At the time, students who took GCSE English and English language were offered special re-sits, even though Ofqual denied there was a problem with marking and the complaints were subsequently rejected at judicial review.
Dr Mary Bousted, general secretary of the Association of Teachers and Lecturers, said: “There is already tremendous pressure on young people to achieve good grades as their futures depend on them.
“All the hard work that they, their parents, teachers and support staff put into preparing them for exams can be undone by the uncertainty of the grades awarded. Not only are schools losing faith in the exam system, but so too are employers.”