The Grill Room, London

It was where Oscar met Bosie in Bohemian splendour. But Tracey MacLeod finds it is the decor, not the food, that is the fairest of them all at the Café Royal's Grill Room

The Grill Room of the Café Royal, London's most beautiful dining room, was also once its most notorious. It was in the Grill Room that the Marquess of Queensberry spotted his son, Lord Alfred Douglas, lunching "in the most loathsome and disgusting relationship" with Oscar Wilde. He later wrote a furious letter to his son, threatening to shoot Wilde on sight, to which Bosie insouciantly telegrammed back: "WHAT A FUNNY LITTLE MAN YOU ARE."

The aesthetes and Bohemians have long deserted the Grill Room, although the Café Royal survives as an eight-storey complex of function suites in the not-too-aesthetic tourist zone off Piccadilly Circus. The Grill Room, the fin de siècle time capsule at its heart, has in recent years only been available for private hire, apart from a brief refulgence as part of Marco Pierre White's volatile empire. Now it's open to the public again, with an executive chef from Zilli's, the small empire of fishy Italian restaurants, and a modern British menu that describes fish and chips as "beer-battered cod with hand-cut chips and minted pea puree". Beer-battered cod at the Café Royal? It's all wrong. The Grill Room is surely the kind of place where a tremulous ingenue should be spoon-fed oysters by her wicked Uncle Jasper. It's French, louche, decadent. It isn't a place to eat fish and chips.

Still, I'd never been there, and it seemed the perfect place to prolong a high-camp evening spent thrilling to Cole Porter's Anything Goes. I'm not currently in possession of a wicked Uncle Jasper, but The Independent's Tony Quinn was ready, as ever, to step into the role of indulgent bachelor chaperone, though he drew the line at wearing a green carnation.

Squeeze past the Café Royal's phalanx of bouncers, and you immediately exchange the brutalities of 21st-century London for a Parisian fantasy straight out of Moulin Rouge. It really is a breath-taking room, a flamboyant exercise in rococo maximalism, all glitter and plush and naked female statuary. The gilt mirrors lining the walls seem to extend the room infinitely, to magical effect. In Salome, Wilde wrote that one should only look in mirrors, and the Café Royal is a narcissist's dream. However multiplied, our reflections couldn't compensate for the fact that the room, once the beating heart of Bohemian London, contained only one other party of diners. It wasn't the way to see the Grill Room at its best. There should be brittle, post-theatre banter, and table-hopping, not a group of Lebanese yuppies talking into mobile phones.

Having got us in, the staff weren't going to let us escape. In the flurry of waiterly attention that erupted around us, it wasn't immediately apparent that some of the decor had seen better days. The loose covers slipped over the tattier red velvet banquettes, for example, imply that the Grill Room's backers are taking a somewhat tentative approach. Also striking a wrong tone was the piped music. We were in a dining room evocative of belle époque Paris, so why were we listening to elevator-ready versions of the bossa nova? As our first dishes arrived, a narcoleptic "One Note Samba" was staggering to a close, a title which proved sadly apposite.

Dressed crab was a savourless Californian edition in which the dill outpunched the crab meat, while "warm salad of good things" was an assembly of ho-hum ingredients – Jerusalem artichoke, puy lentils, roasted tomato, warm goat's cheese – which needed an excellent dressing to make it come alive.

We attempted to go a bit more sybaritic with our main courses, and Tony decided to try lobster thermidor for the first time. As an introduction, it went about as well as Bosie introducing Oscar to the Marquess of Queensberry. "It's cheesy. I didn't know it would be cheesy," Tony mourned, over what looked to be an authentically indulgent combination of lobster meat and mornay sauce. My fillet of "Denham Estate" venison was tender, but seemed characterless, given that we'd been told where it grew up. Supporting vegetables, including cabbage and glazed parsnips, were exactly comme il faut.

Service is of the old-school, attentive-to-the-point-of-annoyance variety. "They're man-marking us," hissed Tony as two waiters darted out simultaneously to fill our glasses. The staff are obviously professionals, though, and looked crestfallen as they took away one of our puddings virtually untouched – an anaemic panacotta served with a rhubarb jelly that tasted of nothing but the cutlery.

At around £50 a head including wine, the Grill Room wouldn't be a prohibitively expensive destination for a special-occasion meal. The room is certainly as special as any in the world. I'm torn; I want people to go there, so a glorious relic can be experienced by as many people as possible. But I can't honestly recommend it for the food.

Here's a compromise. Next time someone visits you from abroad and wants a fancy meal in London, take them to the Café Royal. It will confirm all their prejudices about the British: that we're good at heritage, and not very good at cooking. E

The Grill Room, Café Royal, 68 Regent Street, London W1 (020-7439 1865)