The changes to GCSEs are “deeply unsettling” and will leave people “puzzled”, according to the man who introduced them.

Lord Kenneth Baker, who was education secretary under Margaret Thatcher in the 1980s, has criticised the new numerical grading system, saying that “schools won't understand it, and certainly employers don’t at all”.

He warned that the exam regulator, Ofqual, should be “very wary of making such fundamental changes as this”.

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

The grades were designed as part of a package of reforms to toughen up syllabuses and to cut down on the number of students getting A*s, which has now been split between two grades, eight and nine.