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Rogue Trader Director: James Dearden Starring: Ewan McGregor, Anna Friel (92 mins; 15)

James Dearden's Rogue Trader is - to use a phrase familiar to, and dreaded by, anyone who has ever called a plumber in to unblock a pipe - a right old bodge.

Based on Nick Leeson's own published version of his story, it was produced by the man who once secured an exclusive television interview with him, David Frost (or rather, as he prefers to style himself on the film's credits, "Sir David Frost", which is as pompous a designation as would be "Sir Charles Chaplin in City Lights"). With such a pedigree, then, it shouldn't surprise us that it's a somewhat biased account of the well-documented events which led to Leeson, when appointed Barings' futures manager in Singapore, running up losses so stratospheric they caused the whole bank, like a dud cheque, to bounce. The narrative proper ends with his arrest in Frankfurt, although a trio of closing titles brings us up-to-date with his prison sentence, his divorce and his colon cancer. The only thing left out is that he's now, as I write, on the point of gaining his freedom, and one can't help wondering why the film's producers passed up on the wheeze of postponing its release so that it would coincide with its protagonist's.

Then again, it's not so puzzling after all. There's so much else wrong with this dismally cack-handed film it's hard to know where to begin. With the casting of Ewan McGregor, perhaps. One major problem with Nick Leeson as the subject of a biopic - and this feels very much like an authorised biopic - is that most of us still vividly recall what he looked like, and he certainly didn't look like Ewan McGregor. You would have thought that, for a film-maker, there was real dramatic potential in that fishy, fleshy, expressionless face with the Little Orphan Annie eyes, a potential for glassy inscrutability, always an interesting attribute in an anti-hero; but Dearden, typically, had the dumbest of all ideas, which was to portray him as yet another of the British cinema's lovable rogues. There was Alfie, the horrible prototype, and there was Buster and now there's Nick.

The other characters, too, are all drawn from stock, and remaindered stock at that. John Standing and Tim McInnerney play a pair of Establishment toffs exactly as David Tomlinson and Richard Wattis would have done 30 years ago. As a perpetually bronzed French playboy-financier, Yves Beneyton barks orders through his mobile from one exotic location or another. And Anna Friel, as Leeson's wife Lisa, has as tedious a time of it in the film as her character seems to have had in life. Neither of them is required to do much more than lounge around a hotel pool in Singapore while hubby ever more desperately surfs the telephone.

Friel has, however, the film's one and only cherishable line of dialogue. It's delivered when, aware that Nick's glittering career has mysteriously gone askew but still implausibly in the dark as to the precise nature of his fall from grace, she listens to a CNN reporter assessing Barings' liabilities at upward of eight hundred million pounds. I repeat, eight hundred million pounds. Does she swoon? Throw up in the lavatory? Not our Lisa. She sighs, almost indulgently, "Oh, Nick!", as though the adorable silly-billy has just blown the rent on the third race at Doncaster.

Which brings us to the script, also by Dearden. You've heard people refer to "the worst scenario"? This is it. If one half-closed one's mind, one could defend the recurrent recourse to cliche in the voice-off narration - "O ye of little faith", "I'll leave no stone unturned", "It's like robbing Peter to pay Paul" - on the grounds that this is just how someone with a psychology as terrifyingly banal as Leeson's would speak. But there can be no excuse for the fact that absolutely nothing is made of what was surely the supreme irony of the Leeson affair: that, in the collision of castes represented by his involvement with Barings, it was the sleek patrician elite which found itself pandering to the cheeky chappie from Watford. Nor, prior to that final title informing us of the Leesons' divorce, does Dearden include a single scene suggestive of a marriage in difficulty. The Leesons of the film divorce for the sole and simple reason that their real-life counterparts did, not because of any tensions that have been shown to grow organically out of the narrative. As for what actually happens on the floor of the Singapore stock market, one is either as knowledgeable or as ignorant by the end as one was at the start.

So? A lost opportunity? A good subject squandered? I wonder. It strikes me, rather, that Rogue Trader confirms what I've long suspected: that fiction, be it novelistic, theatrical or cinematic, is a wretched conductor of information, of facts. (I'm a great believer in facts, in their power, their fascination and their innate superiority over fiction, and I would nominate Dickens's Gradgrind as by far the most unjustly maligned character in all of English literature.) It's true that Moby Dick contains a great deal of factual information about whale-fishing but, if one genuinely does want to learn how whales are fished, one turns of course to a completely non-fictional work. Only those who need to have their facts "dramatised" before they come alive for them would go and see Michael Frayn's Copenhagen in order to understand the stature and achievement of Werner Heisenberg: the information conveyed by such a play could be compressed into 10 pages, at most, of a serious biography. And to anyone curious to know what made Nick Leeson and his like tick, my recommendation is: forget the film, read the book, any book.

Incidentally, if I've made no mention of Dearden's visual style, it's because he doesn't have one.