But perhaps, after all, we are underestimating the audience if we think they really buy the story as true. People watching The Madness of George III will accept that George III was mad; they may even accept that he underwent the ghastly treatments depicted in Alan Bennett's play. But the chances are that they will be intelligent enough to know that not all of it happened exactly that way, and the words the king speaks are Bennett's as much as his. None of this diminishes one's pleasure in seeing the play or the film that was based on it.And if people really want to find out, the play or film may lead them to read what historians have to say about it all. Gladiator has inspired exhibitions and books that offer a look at the historical realities. This suggests that more people can tell truth from fiction than we might suppose.

If Enemy at the Gates inspires a fraction of its audience to pick up and read Anthony Beevor's marvellous book about Stalingrad, that will all be to the good.Things are different when it comes to avowedly documentary presentations of history (or "the new gardening" as they call it at the BBC) on TV. Here, the whole point lies in the historical accuracy that such programmes aim to purvey Here the story definitely comes off second-best. The past few years have seen some unprecedentedly intelligent and well-made historical documentaries presented on UK television. Lawrence Rees's series The Nazis: A Warning from History was a particular high point. True, there was next to nothing in the series to justify the subtitle No warning was issued.

As an accurate and intelligently argued presentation of the Third Reich, however, it was hard to fault. It put across some subtle and complex interpretations of Nazi Germany without in any way trivialising its daunting subject.More recently, there has been Simon Schama's gripping history of Britain to marvel at. Deprived of film footage, his portrayal of medieval England depends heavily on his way with words, and Schama's gift of the gab proves irresistible in holding the viewers' attention and convincing them that medieval England was not so incomprehensible after all. Inevitably this involves a good deal of simplification and drastically underplays the strangeness of the past. Yet it doesn't cross the real - and important - line between fact and fiction in any significant way. And in the end, like the Hollywood movies, TV documentaries too can serve to lead viewers on to explore history further, and that, surely, can't be all bad.The author is Professor of Modern History at Cambridge University. His book 'In Defence of History' has just been reissued by Granta Books.