I don't like to think of myself as a spoil-sport. I wouldn't dare question the veracity of Father Christmas, the Tooth Fairy or even the Easter Bunny. But I draw the line at Derren Brown.

Derren Brown's Mind Control TV series on Channel Four has been one of the biggest hits of the year. His 28 date national tour sold out weeks in advance, he has just won an award at the Montreux TV Festival, he is set to conquer America and later this year he will play Russian Roulette on live TV.

His mass appeal relies on his uncanny ability to predict and control human behaviour. He can read your mind, tell if you are lying, plant ideas in your head and mess with your subconscious. The audience is told that this is all down to Derren's stunning understanding of psychology. However, I now believe that his amazing demonstrations of mind reading and mind control are little more than clever magic tricks.

So why is this a big problem? Let's take an example. In one TV show, Derren starts by exposing a simple card trick then states that the rest of show will be different: "That is the only trick you are going to see in the next hour. These are not magic tricks. This is mind control." Throughout the rest of the show he demonstrates his ability to divine people's innermost thoughts. It all seems like impressive psychology, but my suspicions were aroused when Derren apparently mentally manipulated somebody's choice of cards in a game of poker.

He meets three men and picks one, because "through watching the three of you I think that your signals are the easiest to read." Next, Derren shows him ten cards, just enough for two poker hands. He shuffles the card, then deals the top card to himself and the second card to his opponent. He then holds up the remaining cards, two at a time, asking his opponent to choose one, keeping the remaining card for himself. After four such decisions both Derren and his opponent reveal their hands. Time after time, Derren's hand beats his opponent.

It seems that Derren subtly controls his opponent's choice of cards. As with many of his demonstrations, he provides hints about his methods. Derren says to the man, "Are you aware of your own signals when you play a game of poker? You're telling me with your nose which one you're going to go for. This time I am going to rearrange the cards into an order that I can sort of influence you with."

I watched this demonstration again and again and became increasingly suspicious. The truth is that it is nothing to do with psychology or body language. Instead it is a magic trick. Derren selected his ten cards very carefully - three aces, three kings, three sevens and a queen. This combination ensures that whoever has the queen will always lose the game. Imagine you have the queen - the best hand you can possibly have is three of a kind (three aces, a king and the queen). Not bad, but you will still lose because Derren will have three of a kind and a pair (3 sevens and 2 kings). At the start of the game Derren merely has to deal the queen to his opponent, and then he will win no matter what cards his opponent chooses.

In short, this is nothing to do with psychology. It is a magic trick. In fact, exactly the type of trick that Derren denied using at the very start of the show.

In the same programme a boxer and a woman (Derren's assistant) face each other. He places his hands under her arms, hoists her easily into the air and returns her to the ground. Next Derren stares into the boxer's eyes and defies him to lift the woman, having apparently sapped his strength. Sure enough, the boxer finds it impossible to lift her off the ground.

Derren says in narration, "Some athletes use the mind to try and improve stamina and strength, can I use my mind to take it away?", clearly implying that this is a psychological effect, presumably the power of suggestion. Although the power of suggestion can affect people, I am convinced that it does not explain this dramatic demonstration. In fact, this stunt is most easily explained using GCSE physics.

If the woman stands 4 inches from the boxer, then the boxer can lift her. If she stands 8 inches away, then the force required to lift her doubles. It is the physics of levers. Nobody notices that she moves a few inches back or forth, but the results are very dramatic. Once you know what to look for, it is obvious.

What is pernicious about these demonstrations is that the audience is left with the impression that they have watched genuine psychological effects. Derren said in one interview, "It's very easy to get into somebody's mind. I can do it in a handshake or a look. Everyone is very open to suggestion and can be manipulated to get the response you want. It's a mixture of logic, psychology and mind games." In fact, the vast majority of the demonstrations are based upon well-known magic tricks.

You might ask, "What's the harm? Leave the poor guy alone. It's only a bit of fun."

There are three problems. First, any TV performer has a contract with the audience. In this case, Derren's contract is based on a claim to perform effects based on psychology, but this is simply not the case. Often his psychological explanations are bogus. Viewers are left with a false understanding of psychology and an exaggerated idea of what is achievable through the power of the mind.

Derren says, "Giving explanations, which we do some of the time, is not about patronising people. It's about playing to people's intelligence." It is actually about misleading people. Having spoken to several very bright people, it is clear that they are completely taken in by the false explanations. When the truth is revealed, they feel cheated.

I surveyed sixteen people leaving Derren's recent stage show. Eleven people believed that the entire show was based on psychology, as opposed to magic tricks. They had been deceived, because it was nearly all magic. When asked how they would feel if, say, the synchronising minds demonstration turned out to be a trivial trick rather than deep psychology, they all said that they would be annoyed.

The second problem is that Derren's show taints the science of psychology. He makes statements about psychology and what can be achieved with the human mind, but they directly contradict scientific knowledge. Professor Chris French, a psychologist at Goldsmith College, says, " If Derren Brown really has successfully developed techniques to discern the contents of people's minds in the way that he claims, he has single-handedly achieved more than the collective attempts of psychologists over many decades. It may be of some relevance that Brown already had a pretty successful career as a conjurer before he started claiming that he was producing his effects in a different way."

In one of his stunts, Derren appears to claim that he can spot if people are lying, using body cues or sometimes just the voice. He succeeds at spotting lies every time and is even prepared to risk personal injury on the basis of judging the honesty of people's answers. Portsmouth University's Professor Aldert Vrij, an expert in methods for identifying deception, says, "People think that you can use body and voice cues to spot lies, but in fact it is much harder than it seems. There might be some excellent lie detectors but I don't know anybody who can consistently and reliably spot a lie. It is beyond current scientific knowledge. Even polygraph machines are not reliable."

In one programme, Derren places twins in a "heightened state of synchronicity". One twin thinks of a number between 1 and 1,000 and the other, with her eyes closed, writes down the same number! The clear implication is that this is an illustration of some deep scientific psychological phenomenon. However, psychologists have told me that this level of coherence between twins is not possible. Furthermore, I can see exactly how the synchronicity effect is created using a magic trick - it is clever, but it is misleading. Derren is making a mockery of science. Furthermore, the fake demonstration even takes place in a laboratory to give it the veneer of authority.

The third and most serious problem is that this programme taints factual television. Channel Four makes dozens of brilliant factual programmes each year, but this series misleads and appears to elevate magic to the level of science. If the TV audience reacts like the theatre audience, then the response is, "It's all science," or "Oh no, it's not magic. If I wanted to go to a magic show then there are better magic shows than this."

Of course, magic does involve the science of psychology. But Derren implies he is using a branch of psychology distinct from the psychology of, say, magical misdirection.

The ultimate insult appears at the end of the TV show, when viewers are encouraged to visit the Channel Four science website. There you will find Mind Control alongside programmes about the Space Station, the SARS virus and engineering. Putting Derren alongside genuine science serves to elevate his status and degrade the other programmes.

And the problem goes beyond Channel 4. Derren performs his mind reading on numerous chat shows, but again the audience often don't get the full story. In these sorts of demonstrations, the participants are often asked to write down their thoughts before the show starts. Viewers rightly assume that they can trust programme makers to be fair. Not telling viewers about such preparation is an abuse of this trust.

Derren recently appeared on ITV's Good Morning. He was allowed to do a couple of mind reading stunts and explained them by saying, "People have patterns of behaviour that you can identify, and once you've identified them you can manipulate and predict them." In particular, Derren could tell that Philip Schofield was thinking about the death of his childhood pet hamster because he could see, "How you're responding and how you're agreeing and disagreeing and pupil dilation and so on." Presumably if Schofield had been thinking about the death of a goldfish then the pupil dilation would have been different.

Based on his track record and my basic knowledge of magic, I am sure that Derren's Good Morning performance was not psychology. If I am wrong, then please take this demonstration to a laboratory and publish the results. It is always nice to have a British Nobel Laureate.

The producers and presenters of Good Morning are smart people, so I find it hard to believe that nobody on the team figured out that Derren's performance is just magic tricks dressed up as science. Nevertheless, he was allowed to persuade millions of people that one can use psychology to read minds. The production team seems ambivalent about its responsibility to its viewers.

In conclusion, Derren Brown annoys me because he so often presents false explanations for his magic tricks, thereby misleading the public and making a joke of serious psychology. And the TV execs annoy me because they provide a willing avenue for his stunts, not seeming to care that factual television is a precious commodity.

Please do not misunderstand me. I do love magic. I merely hate it when magicians pretend to be psychologists. By the way, I apologise to magicians for revealing the poker trick, but in my opinion Derren only brings magic into disrepute. Giving away one secret seems like a small price to pay to highlight the problem.

My fear is that this is the start of a nasty trend. Reality magic is becoming increasingly fashionable, but TV execs need to be honest with their audience in terms of what they are actually delivering.

Finally, I suppose I should put my money where my mouth is. Derren performed two stunts on This Morning. If he can repeat them - read my childhood thoughts and replicate a drawing that I make - then I will happily donate £1,000 to charity. Derren, if you are happy to accept the challenge, then just contact the Telegraph offices.

Published in The Daily Telegraph newspaper on 5 June, 2003.

Since writing this article about Derren Brown I have been asked several questions; you can find a few brief answers to common questions in my Derren FAQ's page.

In particular, I would point out that some of the points in the article above refer the first series. Also, in an interview with Jamy Ian Swiss, Derren seems to think that I was (at least in part) making some reasonable points.