The teacher was taken on a very long lift ride down into Hell. She emerged into a wonderful landscape of sunshine, beautiful golf courses and swimming pools. For a day she enjoyed the company of former colleagues and long-lost friends, drinking the finest wines and eating lobster for lunch.

After a night in a magnificent luxury hotel, she was taken back to Heaven in the same lift, where she spent the second day strumming a lyre and singing hymns with a couple of angels. In the evening, St Peter reappeared.

“So where would you prefer to spend Eternity?” he asked. “I never thought this would happen,” the teacher replied, “but I think I’ll choose Hell. I really liked the look of it.” “Very well,” said St Peter.

Down the teacher went on the very long lift ride until she reached Hell again. The door was opened by Mephistopheles, and she was astonished to see a barren landscape with garbage everywhere. All her former colleagues and friends were dressed in rags, picking up litter and looking thoroughly miserable.

“I don’t understand,” she said in dismay. “What has happened to that wonderful landscape I saw yesterday, the golf course, swimming pool, lobster lunches and luxury hotel?”.

“Ah,” Mephistopheles replied, “Yesterday was the interview. Now you’re on the staff.”

That story, doing the rounds in various forms, neatly illustrates the gap between fantasy and actuality. In real life it can become a yawning gulf, so advertising agencies and spin doctors, powerful agents of manipulation and persuasion, try to make us believe that no gap exists.

There has been a huge growth in techniques for fusing image and reality. When previously unpopular Richard Nixon became US president, a carefully-crafted campaign had fashioned a new image of him to please voters in every region.

Short television commercials were shot and re-shot to obtain a precisely tailored local version that would appeal to each specific rural or urban audience. It worked. “Tricky Dicky” was successfully rebranded.

Children are bombarded by a variety of selling techniques, some of which are extremely clever. The direct strategy, “Buy Wizzo washing powder or you’ll die in pain”, is now seen as too crude.

There are cigarette advertisements which do not even mention a product name, so potential customers have to puzzle out which brand is being sold. In the process they become more engrossed than usual. Cleverer still, the government health warning becomes the evidence that it must be a cigarette ad. A dire message is thus cunningly disarmed, turned instead into an intriguing clue.

Sponsorship of sport, even on the BBC, involves subliminal persuasion through saturation of the viewer in the sponsor’s “house colours” or logo. Carpets, playing surfaces, billboards, players’ shirts, even their scores, will all display them for hours.

You would expect that teachers who draw children’s attention to these sinister processes would be congratulated. Instead, they run the risk of being attacked. “Media studies” is seen as substandard, or even as a vehicle for subversion.

Yet the national curriculum in English says, at both primary and secondary levels, that children must learn to distinguish fact from opinion; recognise what speakers or writers might do when trying to persuade them; analyse ambiguity and hidden meanings. Looking critically at the intentions behind visual images, or the use of rhythm and music, is also necessary for understanding the dark arts of persuasion.

Back in the 19th century, some patricians thought that the proletariat should not be taught to read and write, as they would probably riot if they discovered what was being done to them. Today’s reactionaries oppose children learning to resist image-makers.

Citizens of the 21st century will need to have a very high level of text literacy as well as an understanding of audio-visual and subliminal persuasion. Otherwise, as the teacher who opted for the PR version of Hell discovered, ignorance of the techniques of deception can exact a high price.