Jan Moir Are You Ready To Order

There is a lot of restaurant action in the film Something's Gotta Give, which stars Jack Nicholson and Diane Keaton. The romantic comedy - like so many real romances - begins and ends in restaurants, although that's where any similarities to real life end. In the Hollywood version of restaurant reality, handsome, smiling waiters deliver mouthwatering dishes faster than speeding bullets, while diners glow in a pastel soup of flattering light as brandy is poured in endlessly generous measure.

Fabulous! Shall we book without delay? No, because almost without exception, these places do not exist - will never exist. For apart from a shot of someone walking into Aureole in New York, the fake restaurants were built on sound stages in Los Angeles and the only authenticity about them was that film stars were sitting at all the best tables.

However, when the location moves to Paris, tactics change. A key scene is filmed in a restaurant that really exists, a brasserie called Le Grand Colbert, which the Diane Keaton character raves about because it serves "the best roast chicken in the universe". A restaurant, known to be one of the prettiest in all Paris, that Hollywood felt it could not replicate? Where something incredibly romantic happens in the film? On this St Valentine's week, chevaux sauvages could not hold me back.

Le Grand Colbert is situated in a tiny street near the Bourse, with a small, but lovely exterior that belies the 100-seat brasserie plunging into the distance inside. Now a listed building, the Belle Epoque-style interior is divided into three sections by etched glass screens. A bar with painted friezes runs down one side, giant ferns sprout everywhere, rich velvet curtains swish, copper lights glimmer and black-leather banquettes form most of the seating. It looks so familiar because it has been copied so much.

Elsewhere, theatre posters are tacked on to mirrors, waiters fly around with Parisian dash, and it's hard not to love a restaurant that serves big bowls of crisps with its aperitifs.

Le Grand Colbert has been here since 1830 and, potato snacks aside, the menu has probably not changed much since then. Snails, onion soup, oysters, choucroute and sole a la meuniere all feature, as do frog's legs, andouillettes and fillets of herring. So far so rigorously authentic, although the wine list is disappointing. These days, it is a mistake to assume that wines will be any cheaper or better in Paris than they would in, say, a half-decent restaurant in London. For example, a Chateau La Bienfaisan 2000, on the list here at £26, will not be ready until 2006 at least - and was not the only immature bottle featured. Our Chardonnay Louis Max (still overpriced at £18) was served so over-chilled that you couldn't actually taste it to moan about it.

However, lovers please note that there is at least one fantastic bargain on the list: a bottle of Cristal Roederer 1996 at £81 - vital lubrication for that special occasion.

"Are we having a special occasion?" I ask S hopefully. He is a nice man, you know, but he begins to look more panicked every year as St Valentine's Day approaches.

"Don't be ridiculous," he shrieks, cramming a crab claw into his mouth, thereby halting further conversation.

Sigh. Like everyone else in the room, we start off with some shellfish - a modest half-dozen Belons that are so small they turn out to be pointless.

"I've seen bigger diamond earrings," says S. He hasn't. He wouldn't know a proper diamond if he found one in his breakfast egg. He's only saying that because it's the kind of thing I would say and he's trying to get back into my good books, although on this night of nights, diamonds are a pretty dangerous topic.

Oh, boy! Fear creeps over his face as he realises this and up goes the crab again. Actually, it is a glorious creature, as fresh as they come and a good deal at £11. Sticking to our film theme, we order pretty much what the stars did in Something's Gotta Give - a Chateaubriand with pommes Lyonnaise and, of course, the roast chicken, billed here as demi-poulet fermier roti aux herbes fraiches.

What can I tell you? The beef is truly tragic, a great big lolloping, flabby cut of meat of indistinct lineage. It looks like a discarded old boot and has clearly been hanging around in the kitchen too long after cooking. It is cold. It has no taste. It has no big crusty exterior and melting pink meat inside, the way it should. Like the wrinkled old spuds that come with it, it looks exhausted. I hate it and the fact that it was even served in the first place.

"The famous chicken," says a waiter, sliding an oval earthenware dish on to the table. I'll say it's famous. Possibly even genetically notorious. My demi-poulet portion contains three legs, which must mean - mustn't it? - that a strain of six-legged fowl is being raised somewhere in rural France, wheeling across the farmyard like a fleet of Mississippi paddle-boats. Diane Keaton wouldn't get served a Jake the Peg portion like this, would she? Of course not.

However, surfeit of appendages apart, the chicken actually is quite delicious, its moist and golden flesh served with a deeply flavoured gravy and a carpet of fresh tarragon. Definitely good to very good, but worth flying halfway around the world for? I think not.

Moving quickly along, we have a pudding thing of piercing unpleasantness, a nightmare of factory flavours, acid colours and spray-on cream - although I did notice a lot of the locals tucking into babas served with a little tot of rum, which looked like fun. They also have a hilarious fake birthday cake, complete with fairy lights and sparklers, which is presented to celebrating customers by singing waiters.

So there you have it. Hollywood Reality versus My Reality. There is a fantastic buzz in Le Grand Colbert, it stays open late 365 days a year, it's always packed and everything about it is exuberant and stylish, except the food. Even the salads are greasy and overdressed, and you will probably have to fight to get a decent table. I know I did.

However, if you enjoyed seeing Jack and Diane snog and thrash around like two old turtles, then don't rule out a grand homage trip here. There is no denying that the surroundings are très romantic and if you are lucky, you just might - like me - end your evening with something small, white and glittering in the palm of your hand. A tooth. One of mine cracked in half on a bit of cheese.

• Le Grand Colbert, 2-4 Rue Vivienne, Paris 75002 (0033 1 42 86 87 88). Dinner for two, excluding drinks and service, costs £55.