Some restaurants are all bells and whistles. They have a theme or gimmick. Their decor ranges from idiosyncratic to downright funky. Their dishes compete to showcase the most unlikely combination of ingredients. Staff mightn’t be wearing fancy dress but you imagine it’s been considered.

Now I’m a fan of bells and whistles. A sense of fun should never be underestimated, nor does it necessarily mean an inferior product. However, there’s also a place in the world for class. Not social class but understated excellence, showcasing quality with the minimum of visible fuss, despite the vast amount of fussing required to produce said quality.

So, Cornus, a new unashamedly upmarket restaurant in Belgravia. Cornus is classical music. It’s a five-day Test match at Lord’s. It’s a tailored dinner jacket from Savile Row. It’s the second venture from David O’Connor and Joe Mercer Nairne, owners of the acclaimed Medlar down the road in Chelsea. Expect Cornus to prove another hit.

With its white walls and white table clothes, dining at Cornus is a soothing experience, the culinary equivalent of a luxury spa, or a very nice cloud. Everything is cloth and marble and walnut. Behind the bar glitters the most tantalising assortment of bottles; I reckon the top shelf is worth more than my flat. There’s a gigantic white one with a literal orb at the top that looks like something out of Mordor.

The team at Cornus are dedicated to their craft: head chef Gary Foulkes earned a Michelin star at Angler and he’s gunning for another one here. You can go a la carte or tasting menu, and there isn’t a vast difference in price between the two, especially if you drop £56 on Phil Howard’s langoustines for a starter. One has to be thorough, however, and thus we went for the full shebang – and most bangy it proved to be.

Cornus – Roast Pigeon ‘des Gourmets’

We start things off with champagne and some amuse bouche. Delightful. The journey begins proper in the shape of a lovely light sea bass tartare flushed with oyster cream, as moreish as it sounds. Then dressed Cornish crab served with avocado and wasabi – the latter is an inspired addition, adding an incredibly addictive sharpness to the rich crab meat.

Cornish tuna with Vesuvius tomatoes is wonderfully fresh, the kind of dish you could be eating in an Italian vineyard rather than around the corner from Victoria coach station. Ditto the roast Newlyn cod, its lovely, salty smell detectable from the plate. Served alongside a persillade of Scottish girolles, squid, crispy potatoes, it’s one of those slices of fish so well cooked that it crumbles at the touch of your fork.

Roast Pigeon ‘des Gourmets’ with chestnut purée proved a richly satisfying headliner. We opted for the Chocolate barquette as a desert: my notes read “very chocolatey, very good” and that just about covers it. You can opt for a three or six wine pairing as selected by the sommelier: wine director Melania Battiston is another Medlar veteran while Lukasz Gorski is the current world young sommelier of the year. As I said, the Cornus team know their craft.

Worth noting that the restaurant was basically full on our Thursday evening visit and nobody was looking at their phones. (I was by far the most guilty but those notes won’t take themselves.) Three gentlemen on a nearby table cultivated a forest of wine glasses throughout the evening. I’m talking double figures: it was genuinely magnificent, like an art installation. I should stress the lads remained the model of decorum throughout – connoisseurs rather than carousers.

What’s the damage? You’d rather not know. Most starters dwell between £20-£30, most mains between £40-50. Bottles of wine start at £38 and finish at four figures. The tasting menu with six paired wines gets you to £500 for two people, without counting the service. You do not do Cornus on the cheap. But for those willing to open the wallet, an extremely classy evening awaits.

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27c Eccleston Pl, London SW1W 9NF; Cornus