Fifty schools were listed - the top seven claimed 100 per cent A* to C grades at GCSE. However, this figure is quite misleading.
The league tables for state schools are published by the Department for Education and give the A* to C grades at GCSE as a percentage of pupils on roll in the previous January (Form 7 census time). Pupils who subsequently drop out of school, or who are not being entered for any GCSE exams, are still included in the total from which the percentage of A* to C grades is calculated.
Also, significantly, state schools enter pupils for GCSE when they feel a grade can be obtained between A* and G. Clearly the leading independent schools are prepared to enter pupils for GCSE only when they can confidently predict at least a C grade. This distorts the apparent achievement of these schools.
If Isis is to publish figures which can be used as a comparison with the league tables for state schools, it must calculate them in the same way.