A former Suffolk headteacher turned union leader has said a rise students gaining top A-level results would not represent a "devaluing of grades".

Geoff Barton - former head of King Edward VI School, in Bury St Edmunds and now general secretary of the Association of School and College Leaders (ASCL) - said this year's students should be celebrated for their achievements following a year of educational disruption not seen since the war.

As students prepare to receive their A-level results on Tuesday, after exams were cancelled for the second year in a row due to the pandemic, Mr Barton played down suggestions of "inflated grades" making it difficult for universities to select accurately and fairly.

This year, students will receive grades determined by teachers, rather than exams, and based only on what was taught during the pandemic.

Teachers have been required to consider mock exams, coursework, and in-class assessments using questions by exam boards.

A social mobility expert warned it could be even harder for less advantaged students to compete on a level playing field this summer, for a variety of reasons, including "grade inflation".

Lee Elliot Major, professor of social mobility at the University of Exeter, said a number of factors were likely to conspire to make it even harder for less privileged students to compete.

These include larger learning loss suffered during the pandemic, inevitable variation in teacher assessments by different schools, chances of appealing against grades and increasing competition for degree places fuelled by grade inflation.

But Mr Barton said: "There has been speculation about the possibility of grade inflation this year.

"It would not be surprising if the distribution of grades is different from years when exams take place, or indeed the grade distribution last year, because this year's approach to assessment is different from other years and making direct comparisons is therefore akin to comparing apples with oranges.

"This does not represent a devaluing of the grades awarded.

"On the contrary. This cohort of students has suffered more educational disruption than any cohort since the Second World War and their achievements are extraordinary in such difficult circumstances and should be celebrated."