The action begins as the Romans are pulling out of Britain, presumably in protest at the climate. In this picture it never rains but it pours - and when it doesn't do that, it snows.

Arthur (Clive Owen) and his knights (he's down to his last half-dozen, which obviously saves on costumes) are crack cavalry commandos from somewhere in Eastern Europe called Sarmatia.

They work for the Romans but can’t have been home in some time, because their accents range from cockney (Ray Winstone plays the aptly named Sir Bors as though he has just come out of an especially thuggish episode of EastEnders) to Welsh (loan Gruffudd, who seems to think his character is called Lancelot du Llandudno).

Their final mission for the Empire is to rescue a Roman VIP who has decided unwisely to build his villa north of Hadrian's Wall, directly in the path of marauding Saxons. Equally unaccountably, producer Bruckheimer seems to have got the Saxons confused with the Vikings, and cast the Swede Stellan Skarsgaard as Chief Saxon. For his part, Skarsgaard adds to the geographical confusion by dressing up as a Judas Priest roadie and playing the whole thing with the deep, American drawl of Lee Marvin.

The VIP turns out to be Ken Stott, overacting like mad with the worst 'ice-cream salesman' Italian accent since Nicolas Cage in Captain Corelli's Mandolin.

KEN shatters Arthur's faith in Roman civilisation by the way he enslaves the local Scottish peasants, many of whom bafflingly speak with Mum¬merset accents. And, like so many occupying powers of late, Ken disgraces himself by mistreating his prisoners of war, who include Guinevere (Keira Knightley), a beautiful Woad princess.

Ah yes, the Woads. Anglo-Saxon scholars will be interested to know that for Hollywood purposes all indigenous tribes of Britain south of Hadrian's Wall have been merged into one, the Woads, who fight under the aforementioned Guinevere, who seems by her accent just to have left Woadean.

Her mentor is none other than Merlin, though not as we know him. He's played by Stephen Dillane, in the same rags the Python boys used to wear when they were being crazed hermits. It's hard to know what religion he's into, but he's definitely part of its militant branch and seems to be suffering from woad wage. Arthur resolves to lead all the villagers to safety, just like Bruce Willis did in director Antoine Fuqua's previous action flick, Tears Of The Sun.

Having achieved this, Arthur and his knights allow themselves to be co-opted by the Woads into becom¬ing a kind of Magnificent Seven (well, six by this time), defending them all at Hadrian's Wall from the hordes of sadistic Saxons. All this might not have been quite so laughably inane had the film's hero been even slightly charismatic.

Screenwriter David Franzoni - amazingly the same man who wrote the excellent Gladiator - seems to have had Russell Crowe in mind for some would-be stirring battle scene rants. Vocally, Clive Owen just doesn't have the equipment. His wooden delivery of admittedly lousy lines evokes not so much a charismatic leader as an embarrassed South London copper giving false evidence on a witness stand.

Instead of impressing us with his heroism, he comes across as a tedious nonentity. This is a career-destroying performance.

Keira Knightley's previous movie for Bruckheimer, Pirates Of The Caribbean, had a sense of fun, ingenuity and Johnny Depp. King Arthur has none of these.

All the knights are unin¬teresting and under characterised, and the promising notion of a romantic triangle between Arthur, Lancelot and Guinevere (which you might think is an obligatory part of any Arthurian movie) is raised for a few seconds and then abruptly forgotten.

The film's pretensions to histori¬cal accuracy will be laughable to most serious students of the Anglo-Saxon period, and in robbing the proceedings of most of its legendary aspects - Camelot, Morgan le Fay, the Lady of the Lake, the Holy Grail and Merlin's magic - the film-makers lose any sense of wonder.

Presumably, Fuqua hoped he was going to captivate the audience that adored Gladiator and Braveheart, but in the light of the success of The Lord Of The Rings, it smacks of idiocy to take the Arthurian legends and delete all the fantasy elements that have helped to make them immortal. With the exception of one pass¬able battle scene on an ice-covered river, the fighting is staged so poorly that it's hard to know precisely what's happening, or why.

There's no suspense, since the villains are strategically inept, and the supposedly sympathetic characters are so feebly written that it's impossible to care even slightly who lives or dies.

It's turgid and tiresome. These events would never have given rise to the rich, universally appealing myths of Arthurian legend. The only moment in the film that really lifts the spirits is the rolling of the end credits.