Only one in five of the students who achieve A and A* grades at GCSE will be awarded the highest grade under reformed, tougher versions of the qualification, the exams regulator revealed today.

Ofqual has set out standards for the numerical 9-1 grading system that will be used in the new GCSEs, which are being phased into schools in England from next year. “Pass” and top grades will be significantly more demanding than at present.

An A in existing GCSEs will broadly equate to grade 7 under the new exams. But Ofqual has decided that only 20 per cent of candidates who reach at least that standard will qualify for a grade 9, which is reserved for the “very highest performers”.

In this year’s GCSE results, more than 30 per cent of pupils who met the A standard achieved an A*, indicating that it will become significantly harder to gain a top grade.

The grade standards will help to fulfil the desire for “explicitly harder” qualifications expressed by former education secretary Michael Gove, who initiated the reforms.

But not all school leaders are convinced that tougher top grades are helpful or necessary. Geoff Barton, headteacher of King Edward VI School in Bury St Edmunds, Suffolk, said: “I’ve never felt pressure from students or parents about the need to discriminate between higher levels of attainment.

“It risks a huge amount of confusion for students, parents and teachers. I think it could lead to a sense of unnecessary elitism. The original idea of the GCSE as a general certificate is a good idea and I’m uneasy about tinkering with it.”

In 2017, the first year that the new grades will be awarded in English and maths, Ofqual intends to anchor them to the old grades and will use statistics to keep them there in later years. This should prevent any increase in the proportions of students achieving top grades, unless there is separate evidence that standards have risen.

The new bottom grade, 1, will be roughly equivalent to today’s F and G grades, and broadly the same proportion of pupils who achieve grade C today will gain grade 4 in the future.

But, as part of the drive to toughen up standards, Ofqual has said that grade 5 will be considered a “pass”. This will be set between the current C and B grades. Controversially, grade 5 will be internationally benchmarked so that it is “broadly in line” with the “average performance of 16-year-olds in countries such as Finland, Canada, the Netherlands and Switzerland”.

This is motivated by the government requirement that the pass grade should reflect the demands made on pupils in “high-performing jurisdictions”, after a series of relatively low rankings for England in Programme for International Student Assessment (Pisa) tests.

But Ofqual chief regulator Glenys Stacey stressed that benchmarking was “not about putting in place any direct links or ties to any grades set elsewhere”. And she cautioned against “simplistic” comparisons, explaining: “It is not right to say simply that a new grade 4 will equal a current grade C.

“The [comparison] is at the bottom of each grade, so that broadly the same proportion of students will get 4 and above as currently get C and above - a subtle but important difference.”

Ms Stacey also said that the use of statistical evidence to link the old and new systems was an important element that ought to give students and teachers confidence. “This will make sure that the year group of students are not disadvantaged or advantaged because of the introduction of the new qualifications, and will provide some certainty about what to expect,” she added.

Brian Lightman, general secretary of the Association of School and College Leaders, welcomed the idea of more “challenge” for the most able students, but added: “I think the most important thing is that clear criteria are defined to describe what the standard of achievement is for each grade, as opposed to a statistical proportion of pupils.

“Employers and universities need to know what young people actually have learned through these assessments. We need to move away from worrying about proportions of statistics and actually talk about learning outcomes.”

Patsy Weighill, headteacher of Bilton School in Rugby, which opened a sixth form two years ago, said: “I think the changes will enable closer scrutiny of the progress made by the most able students, as long as the expectations of their progress are as high as possible. But, unfortunately, I think it will impact on the way oversubscribed schools choose students for sixth form and I worry about it creating a two-tier, very selective sixth-form provision within a locality.”

Ofqual also announced that the new maths GCSE will have two separate tiers with overlapping standards, and that grades 4 and 5 will be available in both tiers.

`Playing games with people’s lives’

Elisabeth Gilpin, headteacher of St Mary Redcliffe and Temple School in Bristol, has mixed feelings about Ofqual’s plan to have more grades at the top end of the ability scale and fewer at the bottom.

“Having more differentiation in the top grades will help universities when they are looking at GCSE grades as predictors of university success,” she says. “We already have really high motivation among the most able students. They really enjoy learning and will stretch themselves whatever the system.

“But having only three numbers at the bottom end of the grading system [below current grade C], compared with four letters, now means this will be quite dispiriting for just under half our national population [people who don’t achieve grade C].”

Ms Gilpin is also concerned about the sheer volume of change, with a new national curriculum, GCSEs and A-levels being introduced at the same time. “We haven’t got the money to pay for cover to free up teachers to write up new schemes of work - they are having to write them in their own time,” she says. “I am concerned about the pace of change because it is essentially playing games with young people’s lives; it relies on teachers being superhuman.”