Every year it is the same. The GCSE results come in and, after a few moments of stunned disbelief, I begin to put together the annual appeal to the board. It is a slow, depressing experience.

I feel like I’m trapped in a looking-glass world, where there are no set rules, no consistencies in marking, and no logical application of mark schemes.

Like every head of department in every school in the country, I could tell you stories which defy analysis: of pupils predicted as grade As and gaining Es, Fs or Us; of pupils gaining Bs whom I know for a fact have not read a single book; of re-marks in which 20 or more pupils go up several grades; and one in particular which I still cherish, of a pupil whom, I was informed by the board, had handwriting so indecipherable that it proved impossible to mark his papers. He gained a B.

I could laugh or cry. Or I could move to a different qualification, which is what I have done. I have had enough.

I have had enough of annual appeals that get nowhere because I am appealing to the people who marked the papers in the first place. They do not want to be wrong, so why change the marks?

After my last appeal, which saw almost no changes, a senior subject officer told me that if I wanted to really understand how the marking is done then I should a) become an examiner (I replied I had done it for four years); b) ask a senior examiner in (I replied that I have done that and it cost pound;500); and c) that I should cheer up, really, because our results were not that bad if I thought about it (I will not tell you what I replied).

And unfortunately, with papers costing up to pound;44 to be re-marked, appeals are becoming more and more the preserve of wealthy independent schools such as mine.

But things are changing. Nearly 200 independent schools now offer the International GCSE (IGCSE), with more switching all the time. Most of these courses are in maths, but English language and literature IGCSEs are also growing in popularity. Oundle, Wellington college, Radley and Rugby have switched to Edexcel’s course (Winchester offers the Cambridge equivalent).

However, the exam does not gain points in the Government’s examination performance tables because it is outside the Qualifications and Curriculum Authority’s control. So why risk one’s standing in the league tables by switching over?

There are many reasons for changing. Undoubtedly, according to Duncan Beal, development manager at Edexcel International, some schools switch as a “protest vote” against coursework and teacher-assessed components. But that alone would not be enough.

“Schools tell us that they prefer the IGCSE’s lesser assessment burden in many subjects,” says Mr Beal. “There is time to explore subject areas beyond the specification requirements, which they say they prefer.”

This freedom to move away from coursework, with all the abuses it is open to, is hugely attractive, and it was the decisive factor for Rugby.

Andrew Fletcher, head of English, said: “The current GCSE is over-prescriptive and conventional. Some pupils feel that it’s a lot of work for not much gain, the sense that the course discriminates more on the basis of effort than intellectual ability.”

Disappointing grades at GCSE can adversely affect take-up at AS-level. But there are other, bigger reasons. As Mr Beal says, this process is down to the “increasing global role of some UK schools. as well as the increasing numbers of students from overseas”.

Many independent schools are beginning to re-position themselves by offering an international education in a distinctly British setting.

The overseas students are increasingly important, especially those from the Far East, and students are beginning to demand qualifications which are recognised globally.

This explains the rapid growth in popularity of the International Baccalaureate. For some schools, the move to the IGCSE is part of an ongoing process of detachment from government-imposed regulations and league tables. Increasingly, such restrictions matter less and less.

The colleagues I have talked to who offer, or intend to offer, IGCSE English and English literature, are genuinely enthused by the liberty it gives us as teachers.

Mr Fletcher says: “IGCSE offers greater freedom for teachers to do what they and the pupils might find intellectually satisfying and interesting, simply by allowing more time to make their own choices of material - via less coursework and a more imaginatively arranged syllabus.”

In theory, one could complete the courses in a year, allowing time to study literary texts which are of real value.

Geoff Lucas said on these pages (“The invisible exam”, TES, December 16 2005) that 40 per cent of independent schools are offering, or thinking of offering, the IGCSE in one or more subjects.

He said: “If this trend grows, any hope of a truly inclusive 14-19 framework will disappear... leaving those in the maintained sector with no choice but to make the most of whatever GCSEs emerge out of the post-Tomlinson settlement. In policy terms, such a prospect would be crackers.”

But this is no policy - it is the market responding to an inefficient and unloved qualification. And crackers or not, the break-up is happening and gaining pace. We are at last beginning to see the death of the GCSE. We should celebrate its passing.

David James is head of English at Haileybury, Hertfordshire