As all exam information is confidential, I suppose my ailment is too. Yet I feel compelled to warn those who might end up taking my place about the intensity and severity of this malady.

The problem is unseen, not because it is all in the mind, but because it is all in the poetry section. It is a kind of insanity which transmits itself from the paper to each candidate, only perhaps for a few minutes, but 400 times as much is forced into my brain over a three-week period, with predictably disastrous effect.

I cannot divulge examples of this insanity in practice, but I will tell you of a nightmare I had at the beginning of the marking season last summer. I dreamt that the poem set for next year’s paper was “The Tyger” by William Blake.

First came the innocent grey sacks containing the exam responses, looking appropriate for use in biological warfare. I began to fidget nervously. Then I saw the actual scripts, stacked into neat heaps, 20 per day, or was it five after meals, four times daily?

Crisp new red pens and HB pencils in neat rows contrasted with the spidery scrawl on the front of the answer sheets. There were plenty of green treasury tags too, those awesome indicators of the dreaded extra booklets.

Then came relief. Not every candidate had written on the same set texts. The bliss of variety. I knew this couldn’t last, and then the wording of the poetry question took my breath away: “What is this poem about? How has Blake written it, and what does it make you think about?” Oh No! Not again!

The pace of the dream increased as the insanity of the poetry responses induced a sort of brain fever . . . there were tigers, set alight by terrorists with flame throwers “portraying” a sense of environmental concern. Apparently the poet had written this poem because tiger tokens were no longer available at his local petrol station . . . the tree people were involved somewhere too, and naturally this poet was “clever” and his poems would be recommended to friends and family at once. The tiger was afraid, and some said he had wings. There was a blacksmith mentioned near the end too.

It was written cheerfully, as the poet had used plenty of smiles, or was that similes? It was written in short verses, because a tiger is short; it was a long poem because a tiger is quite long. It ended suddenly because the poet had nothing else to say, of course, which is why the last verse is the same as the first.

The poem made them think about setting light to animals, about that childhood visit to the zoo when they had bought a plastic model of a penguin. The reference to “the Lamb” provoked some high-level analysis of the development of the BSE crisis. The faces of intelligent children appeared before me - the same children who had written so well about Shakespeare, Hardy and others - but now their faces were twisted with sadistic pleasure as they watched me desperately trying to find something of relevance, something, anything I could award a mark for.

The final imposing image was of burning letters in the sky proclaiming AABBCCDDEFGGAA RGHH in an endless, meaningless pattern.

As soon as I awoke I telephoned the doctor. My dreams were getting too close to reality. Be warned.