Oh dear, Diana's affair with surgeon is a reel bad fairytale

Dir: Oliver Hirschbiegel

With: Naomi Watts, Naveen Andrews, Douglas Hodge

Runtime: 113 minutes

THERE is a scene in this biopic of Diana, Princess Of Wales, when the royal makes an unannounced visit to a hospital to visit the sick husband of a friend. As she strides through the corridors, the eyes of onlookers widen comically, jaws drop, and every gaze shrieks, "Oh my gawd, I can't believe what I'm seeing!"

Cinema-goers will know the feeling as they peer through their fingers at this plodding, muddle-headed, tin-eared mess of hearts and flowers. Part Mills and Boon slush pile, part Hello! magazine guide to history, Oliver Hirschbiegel's drama has its heart in the right place, but its head is as empty as a Made In Chelsea star's bookshelf.

While not quite as bad as one might fear - it has the occasional well-observed moment - it is astonishing that the film comes not from some hack for hire but from the director of the Oscar-nominated Downfall, a portrait of Hitler's final days in the Berlin bunker. Nor can it be excused as the product of Hollywood excess. The makers are Ecosse Films, the British production company that was responsible for the likes of Mrs Brown and Nowhere Boy.

Yet nowhere does there seem to have been anyone on hand to question the overall tone of the piece. It is as if little green men had arrived from Mars, were handed a photo of Diana and a production budget, and told to try their best. As for Naomi Watts as the princess, she might have the same hair colour, but otherwise it is like asking Alex Salmond to play Mr Darcy.

But we begin at the beginning, or rather we do not. Diana is concerned with the final two years of the princess's life, focusing in particular on her relationship with Hasnat Khan, a heart surgeon from Pakistan, and her growing role as a campaigner against landmines.

We see the princess alone in the kitchen of her ivory tower, making beans on toast and clad in leisurewear. If not for a house worth America's national debt, she could be any old wife post marriage split. Plenty of gazing out of windows ensues to signify that this is a woman isolated from the world, yearning to start again. Her main contacts are her many therapists, who talk of star signs and other piffle. It is while visiting the husband of one of these gurus in hospital that she first meets Dr Khan (played by Naveen Andrews).

The hospital visit scene is also where things start to go very wrong. The background extras advertise their presence so obviously they might as well have had flashing lights on their heads. One points and shouts, "That's Lady Di!", lest there be any doubt. Diana, meanwhile, announces that, "When I visit hospitals I get excited." It is the first of many moments - another being when she declares her favourite television programme to be Casualty - that one wishes there had been someone to stride on set and inquire, "Really? That's the line?"

There is much more of the same - I gave up writing down quotes and scribbling "Oh dear" beside them - and lots of imagined scenes besides.

The makers have based their adaptation on Kate Snell's book, Diana, Her Last Love, among other sources. But Khan has said he wanted nothing to do with the book and he has dismissed the film as being "hypotheses and gossip". No-one, except the two people involved, know what went on behind palace doors. That is no reason, the filmmakers clearly thought, why it cannot be made up. The resulting scenes of intimacy are relatively bland - it is a 12A film - but they are so horribly hokey they would make a statue squirm with embarrassment.

At other points the film shows commendable restraint. The crash is left off screen, but it hovers over the opening and closing scenes. Here, Hirschbiegel aims for poignancy and gets it. He also shows the princess as a manipulator of the media, as well as its obsession. Her two sons, meanwhile, are seen only briefly. Charles is a voice on the television.

These outbreaks of sanity aside, the film is as barking as Battersea Dogs and Cat Home at feeding time. Watts does her considerable best, but she is tiny and tottering in heels, while Diana was a glamazon in flatties. She tries the shy Di bearing with head cocked, but merely looks as though she has spent the night in a draught. The voice, meanwhile, is cookie cutter posh. Andrews is afflicted by the same marbles-in-mouth syndrome and at times seems to be not so much acting bewildered as actually bewildered.

The film asks for so much to be taken on trust, or excused as dramatic licence, yet for its part it never takes enough trouble to ring true. Perhaps that is the problem with Diana's story; it is too out of this world for anyone to bring it down to earth. There have been at least nine attempts before this one, any one of which would disgrace an afternoon television schedule. Like a siren, Diana has once more called filmmakers to the rocks.