GCSE (General Certificate of Secondary Education), is normally taken at 16 following a two-year course in Years 10 and 11. It is designed to provide a single system of examination across the whole ability range and to enable candidates at all levels to demonstrate their knowledge, abilities and achievements.

The IGCSE (International General Certificate of Secondary Education) was designed primarily as a qualification for overseas pupils but is now being adopted by an increasing number of UK independent schools in preference to GCSE (particularly in maths and science). Some 90% of HMC schools have adopted the IGCSE in at least one subject

GCSEs may be taken in a wide range of subjects, including some vocational subjects. Most independent schools offer between 10 and 25 GCSE subjects but any one pupil will only be able to take between eight and ten of these. The degree of choice they have will depend on the school. Usually the core is English, maths, a modern language and a science but some schools insist on pupils taking eg French, the three separate sciences or two arts subjects. This can reduce choice dramatically and force children to drop subjects ludicrously early.

Sometimes pupils may take one or two GCSEs early (often ICT, maths, RE or a language) and additional GCSEs in the sixth form. There is a short GCSE course, designed to take half the study time of a full GCSE; the short course in ICT is commonly taken in independent schools.

Passing grades are awarded A*–E but only grades A*−C are widely accepted. Five GCSEs at least grade C, including English and maths, are the usual requirement for entry to sixth forms, universities or many jobs.

It should be possible to give the proportion of Year 11 that have 5 GCSEs including English and maths; and to indicate the achievement of the cohort in a school by assigning a numerical score to each grade and calculating the average. Unfortunately current government statistics do not count IGCSE, so many top academic schools are recorded as having no pupils with GCSE maths. And there are now at least three separate systems for calculating the average score. So good, comparable data has effectively vanished – which was probably nobody’s intention.