Pass marks are set to be lowered for the new, tougher A-levels, as Ofqual promises students will not be “disadvantaged” for being guinea pigs of the new system.

Grading will be especially lenient to compensate for the fact that students picking up their exam results this Thursday are among the first to take the reformed courses, the head of the exams watchdog has indicated.

Setting the grade boundaries lower will ensure that roughly the same proportion of students get top grades as in previous years, under a system called “comparative outcomes”.

A-level courses have been re-designed, with coursework and modules axed in many subjects. The package of reforms, instigated by former Education Secretary Michael Gove, followed concerns from universities that schools leavers were insufficiently prepared for the demands of higher education.

Sally Collier, chief regulator at Ofqual, has moved to reassured headteachers that the exam watchdog’s “overriding aim” is to ensure that this year’s students are “treated fairly” and are “not disadvantaged by being the first to sit these new qualifications”.

In a letter sent to heads earlier this year, Ms Collier said: “We know that students tend to perform less well in the first years of a new qualification, as teachers are less familiar with the content and style of assessment, and there tend to be fewer past papers and other resources.