The Greenhouse, Hay’s Mews, London

The frenetic round of openings on the London restaurant scene can make eating out feel a bit like speed-dating; all those sexy new arrivals tend to distract from the charms of the tried and trusted candidate who's been waiting in the wings. Then no sooner have you started to get acquainted when the flashy newcomer lets you down, or disappears off the scene altogether.

That's when an old-stager like The Greenhouse comes into its own, stepping in like Colonel Brandon to offer solid staying power and low-key charm. In my promiscuous quest for thrills, I'd somehow overlooked this debonair old smoothie, which has been feeding and cosseting the Mayfair set since 1977.

Despite its reputation as a perennial, The Greenhouse has played host to a succession of culinary rising stars since it was launched by Brian Turner. Gary Rhodes worked up his repertoire of updated British classics there, Paul Merrett won a Michelin star, Bjorn van der Horst hung on to it and was working towards a second when he passed the baton in 2006 to Antonin Bonnet, who trained under the French master Michel Bras.

A recent redesign gave me the excuse I needed to make a first date with The Greenhouse, and boy, does it know how to sweep a girl off her feet. From the little table that's discreetly positioned by madam's chair for her handbag, through the trolleys that circulate like vintage Bentleys, bearing champagnes and cheeses, to the emergence of Chef Bonnet at the end of the evening for a cruise'n'schmooze, this is clearly a restaurant that's aiming to be more than a one-night-stand.

A formal, spotlit garden buffers The Greenhouse from the residential street outside, but the low-slung dining-room is standard-issue Mayfair minimalist, with a mushroom-velouté colour scheme, slate floors, and the odd spotlit objet d'art. (The controversial decorative birdcages of the last redesign have thankfully disappeared.) Given the bunker-like dimensions of the room, the effect is more de luxe garage conversion than greenhouse.

The menu, though, is full of surprises. Expecting haute-French classicism, we were taken on a roller-coaster ride of unfamiliar flavour combinations and cutting-edge techniques which place The Greenhouse firmly on the modernist end of the spectrum, and Antonin Bonnet in the vanguard of chefs currently working in London.

He had us from the off, with a duo of sensational amuses, a tube of carrot-flavoured tuile filled with a coconut and celeriac cream, and a spoonful of coriander jelly containing a liquid hit of apple and celery, to be swallowed in one intense mouthful. Next, a vivid mint and pea velouté containing a deliquescent droplet of pea pod jelly, with a grissini of cardamom-flavoured yoghurt to temper the sweetness.

Bonnet's passion for Asian ingredients means that a starter of Limousin veal sweetbreads with caramelised garlic cloves and the leaves and flowers of wild garlic gets an unexpected lift from whole Szechuan peppercorns. Scallops come with a yuzu lime dressing, and a silky purée of liquorice and pumpkin that demonstrated Bonnet's willingness to push dishes further into the realms of sweetness than is the norm. It worked with the scallops, but a main course of wild turbot served with a sweet, nutty couscous and a cardamom-scented foam was unbalanced by the further sweetness of a sticky date and tamarind purée.

The other main course was a perfectly cooked fillet of exemplary beef, with grated horseradish and a beetroot reduction; fabulous, but again that sweet tooth surfaced in a side dish of "confit" Charlotte potatoes which was plain odd.

Overall, though, this is cooking of rare flair and precision, showcasing the highest-quality ingredients and delivering intense flavours with the lightest touch. The atmosphere, too, is refreshingly unstuffy, partly because the clientele seems fairly, well, normal, for a Michelin-starred restaurant in this area. The staff, too, seem relaxed and can even be seen laughing and joking – a sacking offence in most restaurants of this formality.

The only other weak link came with a young sommelier who lost interest when it became apparent that our exploration of the 90-page wine list was going to be limited to one of the younger and cheaper (at £58) white Burgundies, a 2005 Coche-Dury. The look of distant martyrdom that crossed his face whenever he approached our table brought to mind Buzz Lightyear's lament – "Years of academy training – wasted!"

The sweet elements that recur throughout the meal make the desserts seem a less attractive prospect than the superlative cheese board, which reflects the new mood of entente amicale by offering Stinking Bishop and Berkswell alongside a wide range of peak-condition French cheeses. These include a four-year-old Comte, for which I was more than willing to break my informal rule never to eat anything that's older than one of my children.

We ended up as the last customers in the house, working our way through the superfluous (but immaculate) desserts and petit fours while the manager chatted to us. It's a good sign when a date doesn't rush you out to a taxi as soon as the action is over, and The Greenhouse is pretty much the dream date, albeit not a cheap one. Youthful experimentation and stamina, coupled with smooth and confident experience. What more could any woman ask for?

The Greenhouse, 27a Hay’s Mews, London W1 (020-7499 3331)

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Ala carte dinner £60 per head plus wine