CSE has been a success story, playing a vital part in raising the achievement of 16-year-olds. We had waited far too long for a universal qualification for this age group when, somewhat surprisingly, Conservative education secretary Keith Joseph gave the go-ahead. Given Joseph’s concern for the “bottom 40 per cent”, I think he would be pleased to see how schools have used the GCSE, since its 1986 creation, to extend achievement across the spectrum of ability.

Perhaps I am recalling the early years of the GCSE with rose-tinted spectacles, but it was almost the only time when the curriculum led assessment, instead of the other way round. It was surely a golden age, with a variety of assessment patterns to suit the particular needs of each GCSE course. Purposeful coursework was balanced with examination regimes appropriate to the subject in question.

The universality of GCSE soon began to wither as ministers interfered and examinations bodies tinkered, reducing coursework and creating tiering patterns that differed from one subject to the next.

Now the universality of the standard is put at risk by the prospect of students circumventing the certificate in order to take more, and earlier, AS examinations. Tony Little, the head of Eton College, has proposed that his pupils should bypass GCSE.

It has, of course, always been possible for students, whole classes, or even whole schools, to do this. When GCE O- and A-level were invented in 1951, it was proposed that students would not take O- levels in the subjects that they intended to study at A-level. In practice, students did not always know which subjects they would be taking. They wanted as many good O-level grades as possible to put on their university or job application forms. And, let us be honest, everyone likes success.

GCSE replaced the O-level system with a universal standard and this is its strength. It meets the needs of the students who require a broad curriculum, at least up to the age of 16, and allows them to demonstrate their achievement across a range of subjects. University admissions tutors and job recruiters want evidence of achievement in more than a few A-levels.

Equally, the GCSE offers those not going on to advanced study a chance to show what they can do.Their grades are generally hard won although those below C are not given the status they deserve.

None of this alters the need to change the assessment of GCSE as part of the reform of 14-19 qualifications. The Tomlinson committee will surely recognise the poor progression at 16 between GCSE and A-levels and the even poorer progression to vocational qualifications. Nevertheless, Tomlinson’s preliminary report in July recognised the need for an intermediate level of qualification at GCSE standard. It will be important that this is retained in any overarching diploma that he subsequently recommends.

The decision of Eton to abandon GCSEs after 2007 will give its students more time to study a broader range of AS-levels, but will deny them any qualifications at intermediate level. Tony Little will want to ensure that no students are disadvantaged by this. Unlike Prince Harry, who will have plenty to put on his curriculum vitae, most 18-year-olds achieving a B grade in art and a D grade in geography would need a good set of GCSE grades to strengthen their application for higher education. If Eton becomes a GCSE-free zone, it is unlikely to be the place for students of Prince Harry’s ability.

Winchester College has already reduced the number of GCSEs taken by its students. Eton is going further than other schools in omitting GCSE altogether. Among the super-selective independent and state schools, there will be some considering whether to take this course of action. But many state and independent schools have students for whom GCSE is the zenith of their academic achievement. It would be unfortunate if this were devalued by selective schools opting out and creating a two-tier school system - those that take GCSE and those that don’t.

The only beneficial side-effect of schools opting out is that they cock a snook at the league tables, which say nothing about the quality of selective schools (or, indeed, of any other school). The pressure to maximise the number of students achieving five A*-C passes at GCSE has created a misleading measure of a school’s performance. Opting out of the certificate would be one more nail in the coffin of league tables, which, in any sensible 14-19 system, would not exist.

But league tables will not be the driving force in a decision to retain or abandon GCSE. The decision depends on what is right for the young people in the school. And, for all the reasons that schools never bypassed the O-level standard, they should carry on with the GCSE until it is reformed.

John Dunford is general secretary of the Secondary Heads Association