League tables have shown that results have improved year on year.
I think that part of the rise in results is the practice of kicking out low achieving children, however hard they worked.
When I was in the sixth no one got kicked out unless they played truant or were caught smoking or were seriously distruptive. The nice but dim kids were allowed to complete their a levels even if they came out with 2 Es.
I think it would give a more accurate picture of a school if children who failed to complete a course were included in league tables as failing that A-level.