The suggestion that Prince Harry cheated at his A-level coursework did not surprise me. According to a tape recording produced by Sarah Forsyth, Prince Harry’s art teacher at Eton, Harry says that he only wrote a "tiny, tiny bit" of his Art coursework: the rest was apparently written by Miss Forsyth. Any experienced teacher knows that cheating at coursework is rife. It is particularly bad in the so-called "posh" schools such as Eton, where the pressure to get amazing results out of indolent, arrogant students is intense.

I can still see the sly grin on my former deputy head’s face when I asked him why the school’s English results were so good. I had been teaching at his comprehensive in a leafy suburb of London for a few weeks, and while I had been impressed by some of the children’s abilities, I was puzzled how the department had gained 100 per cent A-C grades at GCSE; there were clearly children who were getting marks way below these levels. The deputy head leant close to me and whispered:"We cheat! But everyone does, so it doesn’t matter."

This was back in the days when English was assessed entirely by coursework. All the struggling children were placed in Mrs McCracken’s class – a large, rotund lady with a motherly manner – and she would sit next to them, day after day, "marking" their work. Her marking was very specialised: she would insist they wrote their essays double-spaced so that she could write the correct answers above their shoddy prose. The pupils would then "re-draft" their work – copying her sentences.

When the 100 per cent coursework scheme was disbanded, surprise surprise, the department’s results nose-dived. However, it did not stop the cheating. With English GCSE, 40 per cent of the final grade is assessed by coursework, and roughly a third of the English A-level grade can be assessed by coursework. The same is more or less true for most other GCSEs and A-levels.

Nowadays, cheating usually happens when there is a stressed head of department who is being driven to get amazing results by the school’s head. Such managers feel the need to check pupils’ coursework obsessively, and then bully teachers to get it improved. They never, ever say "Write it yourself", but if the teacher says that there is no way a pupil is going to improve his work, the answer will come: "I am worried that you are just not teaching these children very well. You’re not up to it, are you? This coursework is terrible!" Stinging from such rebukes, I have – on the odd occasion – done a "Mrs McCracken" and received lavish praise and smiles when I have re-submitted work.

Now that I am a head of department, I have made a decision to eradicate cheating. I don’t care if the department gets rotten results in the end: I feel that pupils should learn to think for themselves. I have changed GCSE courses so that we now do a syllabus which offers exams instead of coursework. However, when we decide we would like to submit coursework, the department has agreed to some important rules: pupils can do one rough draft in class, have that marked but not proof-read by the teacher, and then they submit their final copy. No endless re-drafting, no endless teacher annotations.

This said, cheating still goes on. The internet means that coursework can be written by an expert for less than £50, and many literate, harassed parents do end up writing important pieces for their darling offspring. What can a teacher do about this? Not a lot. It is almost impossible to prove plagiarism, particularly if a pupil has had an essay "tailor made" from their first draft.

What worries me is that if the recommendations in the new Tomlinson report on education are implemented, as the Labour Party manifesto promises us they will be, cheating is going to be a lot more widespread. Tomlinson is suggesting that GCSEs should be eradicated and replaced by teacher assessment. You only have to look at how the vocational qualifications, GNVQs, are assessed to know that Tomlinson will lead to mass fraud. Coursework can be submitted three times for these courses and I know, having spoken to colleagues in the further education sector, that much of it is written by teachers under the cosh to get great results. Tomlinson seems to be suggesting that his much-vaunted diploma will be assessed in largely the same way that GNVQs are.

Perhaps the controversy surrounding Prince Harry’s coursework will bring all this to light, and the Government will see sense and throw Tomlinson’s recommendations in the bin where they belong. We must insist that every subject is externally examined, and stamp out the cheating once and for all.