Bar Boulud 66, Knightsbridge, London, SW1

Can Daniel Boulud weave his New York magic in the UK? And is it worth braving Knightsbridge to find out?

It's generally agreed among Londoners with an abiding fidelity towards their city that the last place you want to spend a Saturday afternoon is Knightsbridge.

Not since the fabled exhibition of Japanese culture that took place between 1885 and 1887 has this segment of SW1 been redeemed from its reputation as a shining vestibule of affluent stupidity. Yes there's Hyde Park down the road, and the Serpentine Gallery, and Cadogan Hall around the corner, but arriving by Tube, as you will, can't leave you in much doubt that this sliver of riches, named after a crossing of the now subterranean River Westbourne, is a kind of refined urban hell. The crowds squeezing into both exits at Knightsbridge station, to seize on just one example, are akin to the annual attendees of Mecca squeezing into a Ford Fiesta.

But what Solzhenitsyn called "the censorship of fashion" is a barrier to sound judgement, and such is the fuss about Bar Boulud, opened a few weeks ago in a previously defunct part of the Mandarin Oriental hotel, that running this weekend gauntlet promised sufficient reward to motivate your correspondent.

Daniel Boulud left school at 14, worked in France with chefs of the quality of Roger Vergé, Georges Blanc and Michel Guérard, later moved to Copenhagen, and won three Michelin stars for his namesake restaurant in New York, one of two in a city that he has gastronomically conquered.

His claims on each customer's affection begin with the impression that he, too, understands the horror at street level, and is therefore polite enough to tuck you away on the lower-ground floor. The lack of natural light is unpleasant, but the tint of terracotta, abounding wooden panels, and welcoming leather interiors – by New York designer Adam Tihany – combine spaciousness with intimacy, an effect Tihany may repeat in this hotel at the soon-to-open Foliage restaurant, where Heston Blumenthal will be kitchen executive.

There are two main rooms at Bar Boulud: one, with a slinky, curved bar, is a bit Yo! Sushi, but the bigger, more sedate front room recovers in class what it lacks in razzmatazz.

The fixed-price menu, with three courses at £20 between noon and 3pm and 5.30pm and 7pm, must be among the best value in London, albeit with the disgraceful absence of a vegetarian main course. This level of pricing attracts a likeable clientele; some (ahem) young couples, a few suits, haughty ladies-wot-lunch, and families with squealing tots: an ideal mix.

My companion and I excitedly order extra starters – both of which disappoint. The poulpe grillé (octopus, with a spoonful of baba ghanoush, over a tomato and chickpea panisse) does not taste fresh enough for its £9.50; but, much worse, the "Chop-Chop" salad never becomes more than the sum of its parts, even after the unnecessary addition of half a lobster at £15. But from the fixed-price menu, the coarse pâté has just the right bite-ability, and the chilled pea soup benefits from a rosemary cream that gives it the sense of an emulsion.

On to the main course. Mr Boulud is famed for his burgers, and the "Yankee" has a punchy flavour, albeit one diminished by a dry brioche bun and iceberg lettuce, a useless substance that is a threat to the case for intelligent design. The seafood linguini with taggiasca olives is suitably syrupy with the flavour of preserved lemon rind, and its decoration with pine nuts makes it the highlight of the meal.

Wines by the glass lubricate each dish without busting the budget; ranging from £5-£15.50 for the whites, and £5-£12.50 for the reds, they include a fine 2009 Picpoul (£5.50) and 2009 Beaujolais (£8.50). Bottled wines start at £21. These lay the foundation for a superb bittersweet chocolate mousse with intense, fresh raspberry jam and Sacher biscuit, a clever coalition of contrasting textures, and an aromatic custard cake with brandied cherries. So charming is this conclusion that we order a glass of dessert wine at the sommelier's recommendation. He delivers iced cider, which, though a frightening £15 per glass, is wonderful.

Nearly, in fact, worth going to Knightsbridge for.

14/20

Sores: 1-9 stay home and cook, 10-11 needs help, 12 ok, 13 pleasant enough, 14 good, 15 very good, 16 capable od greatness, 17 special, can't wait to go back, 18 highly honourable, 19 unique anmemorable, 20 as good as it gets

Bar Boulud, 66 Knightsbridge, London SW1, tel: 020 7201 3899. Lunch and dinner daily. £124 for lunch for two from fixed-price menu, extra starters, six glasses of wine and service

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Reviews extracted from 'Harden's London and UK Restaurant Guides 2010'. www.hardens.com