Christopher Ray, of Manchester Grammar School, said favouring state pupils would not necessarily broaden universities' social mix.

BBC: Don't handicap private pupils, says leading headmaster

The headmaster of Manchester Grammar School, Dr Christopher Ray, says the impending changes convinced him to move away from GCSEs completely.

BBC: Q&A: GCSE v IGCSE

Christopher Ray, of the Headmasters' and Headmistresses' Conference, which represents independent school leaders, told BBC News the new system could potentially harm "students who only when they get their AS-level results in Year 12 realise how bright they are, who are perhaps in an underperforming school or college and who suddenly have the self-confidence to aim for the stars".

BBC: A-level plans may 'threaten uptake of tough subjects'

What may unify and solve these puzzles is a theory that was first proposed in 1993 by Robert Duncan of the University of Texas at Austin, and Christopher Thompson of the University of North Carolina at Chapel Hill, to explain the then newly discovered gamma-ray repeaters.

ECONOMIST: Pulsars