Until the 1980s schools were required to pay a basic registration fee for each pupil and then the subject fee on top of that, a fact which tended to tie the entire school to one exam board.

However, when the registration fee was scrapped, headteachers tended to devolve responsibility for choice of exam board to heads of department who opted for thesyllabus and board most sympathetic to their style of teaching and which would produce the best results.

Locally managed schools often require more for their money. Mick Hill, deputy head of Ashington High School in Northumberland said: “We expect support courses, supply cover for teachers on courses, exam papers that arrive on time without error and someone on the end of the phone when we run into problems. ”

John Dunford, headteacher of Durham Johnston School, Durham, and president of the Secondary Heads Association, said schools were prepared to turn away from exams that seemed to be unfair to candidates, that seemed to be out of step with their teaching methods or had obscure wording. He said: “If an exam isn’t to our liking then we don’t stick with it.”

However, as a member of the BTEC council who will be involved in merger talks between BTEC and London Examinations, Mr Dunford believes that a body that can supply a whole package across acad-emic and vocational courses could attract customer loyalty once more.

Nevertheless, since performance in league tables is now regarded as crucial to schools’ success, they have become acutely sensitive to how pupils fare under different exam boards and are prepared to switch if evidence shows pupils fare better in a subject under one than another. At Ashington, for example, Dr Neill Travers, head of science, came under pressure from his headteacher to drop MEG’s prestigious Nuffield Co-ordinated Science course in favour of an easier syllabus to boost the school’s GCSE results.

Mr Hill said: “We felt Nuffield favoured grammar school, middle-class kids, just by the nature of the assessment. We have to look at how students relate what they have learnt to exercises given in exam conditions. Art is notorious. You can get ridiculously low grades with one exam board, change to another and grades can suddenly improve.”

The publication of new GCSE syllabuses, he said, meant that all schools were looking again at what different exam boards had to offer. He said: “We spend more than Pounds 30,000 a year on exam fees and for that we require a good service.”

Mike Brown, deputy head of Thirsk School, North Yorkshire, said his school was venturing into vocational qualifications and would be attracted by any board that smoothed the difficulties involved. He said: “This is a big step for a school of this size (900 pupils). What would persuade us of the worth of a board, would be one that offered a simple way of recording and assessing GNVQs. The administrative burden has got to be reduced.”