Frank Chalk explains why school league tables are a bad idea:
The BBC have reported that schools are not doing enough for their best pupils. The truth is that many State Schools massively let down the top and bottom ends of their intake. All their resources, including the best teachers; are concentrated on the kids who are on the C/D borderline at GCSE because that is what affects the school’s position in the League Tables.
Incidently, the reason why the tables matter to schools is that the higher up you are, the more nice kids you get applying and the less chance of getting swamped with the grot.
Indeed it should have been obvious that if the league tables matter, that schools would game the system to improve their posiiton. (And if the tables don’t matter, then why bother having them?)