England's school examinations regulator said it had made a mistake with the way it awarded grades to school students in England after their exams were cancelled due to Covid-19, and the grades would now be based on teachers' assessments instead.

Roger Taylor, chair of the Ofqual exam board regulator, said the body had taken “the wrong road” and had to change course as he offered an apology to students and to schools.

The government has faced days of criticism after Ofqual used an algorithm to assess grade predictions made by teachers, and lowered those grades for almost 40 per cent of students taking their main school-leaving exams.

Media reports had earlier suggested the British government was working with regulators on how to resolve the escalating row.

A spokesman for Prime Minister Boris Johnson said the government was continuing to work on a solution, and that Johnson had spoken with education minister Gavin Williamson and other officials on Monday morning from his holiday in Scotland.

“The whole of government has been, and continues to work hard to come up with the fairest system possible for pupils,” the spokesman said.

Results for separate exams taken by mostly 15- and 16-year-old students are due to be announced on Thursday, and were due to be subject to the same regulator moderation.

The row had damaged Johnson's core message to voters since he was elected in December, which was that he wanted to get rid of barriers to achievement and help those from poorer backgrounds and areas achieve their potential.

Anecdotal evidence from students shows some were downgraded several levels by the regulator's model and missed out on university places.

The devolved government in Wales announced on Monday it would use teachers' predictions for all exam results, and Northern Ireland's assembly said Thursday's results for 15- and 16-year-olds would be based on teachers' assessments.

Analysis of the Ofqual algorithm showed it to result in “manifest injustice”, said Paul Johnson, director of the Institute for Fiscal Studies think-tank, writing for the Times newspaper.

He said it favoured students in the smaller classes more commonly found at fee-paying schools, and, by basing its predictions on past performance, made it harder for top pupils at historically poor-performing schools to get the best grades.