It also found that the majority of 117 teachers in an online poll by the Teacher Support Network conducted with Radio Five Live said the drive to improve grades was compromising their professionalism. Of these, 68 per cent said they helped their students more than was appropriate to raise results.

A former information technology teacher from Dorset told the BBC programme that his head had threatened to ruin his career after he blew the whistle on coursework cheating.

The teacher said he had initially succumbed to the pressure himself. He said: “I was told my pupils had to get a C grade no matter what.” So he said he told his students what to write.

While covering a colleague’s science lesson, he had asked pupils questions about an experiment they were writing up as a coursework assignment. They were unable to answer and then admitted they were just writing up what the colleaguehad told them to say about the experiment. The teacher went to the head to complain.

The teacher said: “I was told clearly, ‘Don’t forget I write your reference. As soon as you apply, for a reference, you’re not going to get a job. I’m going to ruin you basically.’ ” The teacher has since left the profession.

A design and technology supply teacher from Leeds said one of her schools had a filing cabinet with extracts of text which staff could insert into students’ assignments to guarantee C grades.

She said she would write suggestions of how pupils’ work could be improved on sticky labels, which could then be removed so it would not be picked up on by exam board moderators. Changes to GCSE coursework are being introduced in 2009 which will require assignments to be carried out under more supervision in eight subjects, ranging from history to religious studies, in a drive to combat plagiarism.

It is not clear that serious measures will be taken to stop teachers bending the rules. They are likely still to be supervising, marking and authenticating assignments.

Five Live Report: Teaching Taboo, Sunday 11am 7.30pm