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.

“Using statistics [to set grade boundaries] compensates for this expected small drop in performance, so that students in the first cohort are not disadvantaged.”

The package of reforms were instigated by former Education Secretary Michael Gove

Last summer, students sat exams in the first 13 reformed A-level subjects, and this year a further 11 new subjects will be added, including modern foreign languages, geography, music and religious studies.

Boys are expected to score more A and A* grades than girls in the new A-levels, according to a Buckingham University report.

It predicts that boys' performance will improve this year in England because there are twice as many new tough A-levels, which are tested by exams, rather than coursework.

"It appears girls are more conscientious and apply themselves to coursework while boys get rather bored with doing this but are much happier to throw themselves into a final revision effort for an exam to see what they can do,” said Professor Alan Smithers, author of the report.

Using statistics compensates for this expected small drop in performance, so that students in the first cohort are not disadvantaged

He also said that a surge in unconditional offers means that students may have “taken their foot off the pedal” which could lead to a fall in top A-level grades this summer.

Barnaby Lenon, chair of the Independent Schools Council, said: “With the abolition of modules, A-levels are obviously are more demanding as you need to retain the full two years of syllabus in one go, without the opportunity to take resits.”

Mr Lenon, a former headmaster at Harrow School, added that while A-levels are harder, “this year’s cohort are protected due to comparable outcomes. The grading process will compensate for that so you might not need as many marks as you think to pass.”

Exam results are to be downgraded as a measure of school quality by Ofsted, according to leaked proposals which surfaced over the weekend.

The move comes as the chief inspector seeks to crack down on an “exam factory” culture in schools, where a broad curriculum has been sacrificed in favour of cramming for tests.

A new inspection framework, which will be brought in next year, will see exam results replaced with "quality of education" measure, the proposals say.