Schools are already making professional judgements about the quality of teaching and learning, the standard of marking and the preparation and planning of individual teachers.

BBC: Performance pay: Head to head

Mr Lightman, leader of the Association of School and College Leaders, told MPs that he believed that the exam grades for pupils taking the English GCSE in the summer had been been forced downwards in an attempt to balance an "over-generous" marking in January - in a way that was unfair for individual students.

BBC: Heads tell MPs exam watchdog 'failed' in GCSE grades