The Sheraton Park Tower isn’t one of London’s prettiest hotels. Looming over the pavement next to Harvey Nichols, its crude concrete bulk feels like a loutish sink-estate expletive among the polite vowels of Knightsbridge and Belgravia. That may explain why it has taken me so long to visit the restaurant on the ground floor: One-O-One has been here for eight years, but the 1970s lumpenness of the building has always put me off.

Still, both the room and the menu have had a revamp, so I thought I’d give it a go. The clincher was a tip-off that you no longer have to cross the hotel lobby to go to the loo. Just imagine – a loo that’s actually inside the restaurant.

I looked up the restaurant’s number on the website. “To those who are familiar,” says the mission statement, “a fresh, invigorating world of windswept nature and daily renewal awaits. For those who plan a first visit, it is a new, arresting experience and a discovery by the water’s edge.” Windswept nature and daily renewal for the familiar? Are you whisked off to the Falklands for stem-cell treatment if you inadvertently address the maître d’ too chummily? Luckily, it was my first time.

From looking at the menu, it’s clear the chef is behind this elegiac overenthusiasm. Pascal Proyart comes from a family of Brittany restaurateurs, and his cooking is built on a passion for seafood. The dinner carte is divided into sections called things like Delicacies from the Shore and Beyond, and Low Tide and Wonderful Discovery, offering everything from oysters three ways and variations on a Norwegian king crab to cod loin with chorizo. Sadly, the Gallic charm of his descriptions is murdered in translation (in French, low tide – marée basse – speaks of beachcombing romance; the English conjures up dead seagulls, shoals of bobbing condoms and exposed sewage outflows).

Two of us went at lunch time, when a more pared-down menu spares you the poetic tidemarks. The waiters, dressed curiously in white shirts with aquamarine dog collars, arrived with a basket of decent rolls and some mounds of butter, saltily laced with Brittany seaweed and embossed with a tiny oyster-shell motif.

Someone has clearly tried to give the place some glamour, though the room still has the unmistakable whiff of corporate cold comfort that is the curse of modern hotel restaurants. There’s a bar, centred on what looks like a giant white surfboard, and a separate dining room, done out in what are doubtless meant to be the shimmering hues of oyster shells and the seabed. The wood panelling on the walls gave me posttraumatic flat-pack flashbacks, and the chillout background music just wasn’t.

One-O-One’s location makes it prime ladies-who-lunch territory, but on this occasion the ladies must have been lunching in St Tropez. The place was tumbleweed quiet, save for us and one other couple, whose rotund figures echoed their rotund silence. I suspect most of the restaurant’s usual customers are businessmen who drift in from the hotel.

But I genuinely hope this was just a slow day, because the food here deserves better. Proyart is a gifted and imaginative chef. His dishes come together on the plate with a quiet drum roll that is clearly designed to catch the attention of passing Michelin-guide inspectors. It’s the sort of intricate, slightly anal cooking that somehow feels as though it belongs to a different time and place, but there is something strangely refreshing about that.

Naturally, it all comes with a concept – smallness. Our lunch menu offered nine petits plats – three cold starters, three warm and three mini “main” courses, the idea being that you order one of each. We started with Britanny blue-lobster macedoine, red king-crab pastilla, aromatic dressing and apple sorbet. This was culinary performance art. The macedoine – a posh Russian salad studded with sweet chunks of crustacean – was topped with cucumber jelly and caviar, and accompanied by a crisp crab puff and vivid sorbet. Oak-smoked Scottish salmon with fennel blini, cockles and sea asparagus was another poised dish, the salmon, samphire and bivalves perked by a hint of orange.

The best of the warm starters was pan-fried Norwegian scallops with onsen quail’s eggs, pork belly, truffle and potato mousseline. (I had to look up the “onsen” bit: it’s a Japanese method of soft egg-coddling, apparently, originally used in hot springs, though whether Proyart had a geyser out the back with his arresting waterside discoveries, I can’t say.) This was luxurious comfort food – bacon, egg and scallops, like a royal breakfast.

Bouillabaisse with red mullet, small Brittany shellfish, rouille and seaweed mouillettes (basically croutons) was a decent enough soup, although, for me, it was a little shy on fishiness. The maître d’ passed on the chef’s instruction that the mouillettes were to be introduced into the soup one at a time to avoid sogginess. Like I said – anal cooking.

My main course of halibut with langoustine dumpling, paimpol coco beans, truffle cassoulet and the crayfish-based sauce nantua was gentle and rich, topped with a pristine nugget of snowy fish. Scottish beef fillet with redwine sauce was a fine piece of meat, but felt a bit like a fish out of water in this company. We finished with cheese, including a filthily ripe époisses, which, the maitre d’ explained, was “trying to run back to Burgundy”.

Portions are barely more than a few mouthfuls. Prices verge on the wallet-clenching. With the cheese, water, wine and a glass of champagne to start, our three courses for a reasonable enough £30 a head (you can also have two for £20 or four for £40) ended up costing the best part of £145 for two, plus service.

The room threatens pretentious haute twinkiness, but, in the event, the service was attentive without being cloying. The sommelier, who suggested two great wines by the glass, was a young gentleman from Verona. Before we left, I asked if he could recommend somewhere good to eat there. He thought for a minute, then scribbled down the names of two restaurants owned by friends, along with annotated maps showing how to find them.

The stars are for the food and for the staff. I just wish it was a less soulless room in a less dismal building.

AA Gill is away

101 Knightsbridge, SW1; 020 7290 7101
Lunch: Mon-Fri, 12-2.30pm, Sat-Sun, 12.302.30pm; dinner: 6.3010pm

5 stars: One in a million; 4 stars: One to watch; 3 stars: One of many; 2 stars: One-trick pony; 1 star: One in the eye

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