Most people will have welcomed the planned introduction of average points scores to GCSE results tables and the decision to set at least one GCSE target in the same way. This seems to signal the end of the five A* to C grades that put such emphasis on the achievements of the able, and undermined the attainments of all students.

But is it as simple as that, or are we walking into a new minefield?

Imagine two secondaries, each with a similar intake - perhaps measured by a mean cognitive ability test score at 11 - and each with a year group of 200 pupils.

In one, Arkwright Academy, the staff and governors have for many years believed that it is educationally sound to enter each student for no more than nine GCSEs, thereby enabling them to concentrate their efforts and to pursue the many other activities that the school regards as valuable. All their students undertake work experience, and many complete the Duke of Edinburgh’s award scheme. Others participate in the wide range of activities the school offers to help students widen their interests, work with others and gain self-esteem.

But the head and governors of Boulton College believe that academic achievement is everything. Other activities have been curtailed, and it’s all noses to the grindstone to raise attainment. Nine GCSEs - peanuts! It’s 12 each for the Boulton students, and on that basis they regularly do well in the five A* to C leagues, but really fancy their chances in the new regime.

In 1999, a strange thing happened. Every one of the 200 Arkwright students achieved four A grades and five Bs in their GCSEs. Oddly, none achieved an A*, but never mind. It was a record year by any standard - 100 per cent five A* to Cs, and an average points score of 58 (4 x 7 = 28 + 5 x 6 =30). Top of the league stuff, no question.

Boulton College also had a strange experience. Their candidates, too, had a bumper year, all of them achieving a grade C in every exam they took - 12 Cs each. A bit odd, but there was nothing below a C, so the five A* to C rate was immaculate, and the average points score was (12 x 5) 60 each, so that shouldn’t be too bad. Not too bad - it’s brilliant, and knocked Arkwright off the top.

This may be an exaggeration, but there is a little tale of morality, humanity and values contained within. Are we really going to introduce a scheme that encourages schools to increase the number of entries per candidate? Because, sure as eggs is eggs, an average points score will have this effect. The more exams you sit, the more points you get. The more points each individual student gets, the higher the average points score gets. QED.

So, we might argue, let’s prevent that by concentrating on the average points per entry, either as well as, or instead of, points per candidate. But that has the reverse effect. Every G grade scores just one point, and so lowers the average score for each entry. There is no point in entering a student for an exam if they will perform poorly, because this will have the effect of reducing the points-per-entry score.

And if we publish both alongside each other? Imagine the joys of entry meetings, the fascinating decisions about who will do what and even the letters to parents: “Dear Mr and Mrs Morris, We regret to inform you thatI However, should you wish Esther to be enteredIPounds 14.50 by Tuesday, February 13.” It could never happen. Could it?

What is really frustrating is that there is a simple solution close at hand. Several years ago, when the Audit Commission and others looked at added value from GCSE to A-level, they did so on the basis of GCSE performance in English (language), mathematics and the best five other results. As there were no starred A grades, that gave a maximum score of 49, from which A-level projections and performance in added value terms were calculated. Surely this provides the level playing field that we now need? Perhaps a refinement or two would help. For example, by including science, and then having the best four other scores, we could bring qualifications at 16 more into line with national assessment tests’ emphasis on the core subjects.

We are about to embark on what seems to be a better road, so it is frustrating that we haven’t taken the one short step of refinement that would improve it beyond measure. Or have I missed something? Are 12 or more GCSEs really the educational Holy Grail?

Wilson Gleave was a secondary head for more than 10 years before moving to work as an education officer with responsibility for school effectiveness. He writes here under a pseudonym