The number of children receiving the top GCSE mark is expected to be cut in half under new reforms.

Students will receive their results for the first time under a system which uses grades nine to one, rather than from A* to G.

But grade nine is reserved for pupils who demonstrated “exceptional performance”, with only a few hundred students expected to achieve the coveted clean sweep of straight nines.

The new grades were part of a package of reforms by former education secretary Michael Gove, designed to toughen up syllabuses and to cut down on the number of students getting A*s by splitting it between the two highest grades, eight and nine.

Pupils will be marked under the new system for English Literature, English Language and Maths, while the rest of their subjects will be marked under the old A* to G grades.

Ofqual, the exam regulator, said that just two per cent of students – roughly 16,000 - will be awarded grade nine for English Language this year, compared to four per cent who got A* last year.