More changes to GCSE and A-level grades have been made following to school challenges, according to new data released by Ofqual.

It showed that there has been a marked increase (42 per cent) in the number of schools questioning the assessment of their pupil's exams.

In 2014, across England, Wales and Northern Ireland, 77,400 grades were amended, compared to 54,400 in 2013, Ofqual revealed.

While this is cause for concern for some, the regulator was keen to add that the variation in data could be a consequence of the exam system.

For example, there have been modifications made to early entries and resits, resulting in a boost in the number of people sitting exams during the summer of 2014.

Commenting on the news, Brian Lightman, general secretary of the Association of School and College Leaders, said that he was not surprised at the results.

"Many schools have told us of a worrying number of results which simply did not reflect how well students should have done," he said.

"In an informal poll we carried out of 200 schools, 95 per cent said they had submitted appeals and 25 per cent had seen changes to their students’ marks.

"There is a growing lack of confidence in the exam system which has been exacerbated by frequent and ad hoc changes to qualifications."

Mr Lightman added that this constant flux has been confusing to all stakeholders – parents, teachers, pupils and employers – and created distrust.

Schools, he continued, need to feel confident that the marks their students receive are correct.