Notwithstanding this, one of the pleasures of films like Brideshead is usually the guarantee of the presence of at least one or two of our finest actors, and the chance to revel in the familiar tics and nuances of their performances. This is where the film comes most unstuck. The central role of Charles requires an actor to be more or less a cold, blank canvas, and Matthew Goode carries it off perfectly adequately. As Julia, Hayley Atwell seems also to understand the material. But the most important of Waugh's other characters are simply badly cast.

Rather than grand and tragic, the Marchmain family here looks like a bunch of eccentrics with a thing about religion. (Contrary to press reports, the screenwriters Jeremy Brock and Andrew Davies has kept much of the Catholicism intact.) As the matriarchal Lady Marchmain, Emma Thompson manages for much of the time to rein in her tendency towards a kind of Alan Bennett low camp. But it just can't help slipping out. There is something about the facial expressions she uses - the neurotic, worried look, the lip-biting - which work perfectly in a role such as the housekeeper in The Remains of the Day, but which are irritatingly misplaced here.

Michael Gambon plays Lord Marchmain as a dilapidated, rather comical old roué, with none of the authority and elegance captured so well by Laurence Olivier in the TV series. As a result, there is no particular significance or sense of moment in what should be the climax to the story, which is when the old man comes home to Brideshead to die.

Worst of all, though, is the portrayal of Charles's first love, Sebastian, who despite disappearing quite early on in the story remains its most potent character, and has become virtually an icon of the broader culture. Having recently re-read the novel, I can recall no description of him as looking, sounding and moving like a particularly camp chorus boy from a West End show, but this is how he is presented to us by Ben Whishaw, a new young actor who has had praise heaped on him for his theatrical work but who is not known in the cinema. He seems to have based his performance on Tom Courtenay in The Dresser, and it jars badly from the start. Anyone who saw Jude Law as Lord Alfred Douglas in Wilde a decade ago would know that Sebastian Flyte was a part he was born to play. That moment might have passed, but there are surely still enough young actors around to choose from.

Or maybe there aren't? People have lost interest in in the subject-matter of Brideshead. Popular culture has changed more radically in the years since 1981 than it did in the four decades after Waugh wrote his novel. He later wrote that perhaps it had been too pessimistic. I wonder what he would have thought of Big Brother.