Thyme, The Hospital, London, WC2

The Hospital is not exactly your standard NHS issue. Enter the large, light reception filled with iconic designer chairs, and you are greeted with joy by a gorgeous, waif-like Heidi with long blonde plaits, who is playing a computer card-game while holding a telephone to each ear. It's enough to make you sign in for a reverse vasectomy. If you had had a vasectomy in the first place. Or even if you hadn't.

The Hospital is not exactly your standard NHS issue. Enter the large, light reception filled with iconic designer chairs, and you are greeted with joy by a gorgeous, waif-like Heidi with long blonde plaits, who is playing a computer card-game while holding a telephone to each ear. It's enough to make you sign in for a reverse vasectomy. If you had had a vasectomy in the first place. Or even if you hadn't.

Not that Hospital is a hospital any more. It is a "creative" (eek) private members' club, brainchild of former Eurythmic Dave Stewart and Microsoft entrepreneur Paul Allen, and comprises a library, games-room, viewing theatre, gallery, television studio, three bars, a private dining- room and a restaurant.

Post-Heidi, it's a flight of stairs up to Thyme, which used to be in Clapham until it did a Colleen McLoughlin and went shopping for lots of designer clobber, and started mixing it with the high rollers.

Not that there was anything wrong with the old Thyme. It was romantic, well-tended and wine-driven, with uncompromising, affordable food from chefs Adam Byatt and Adam Oates. I thought it was enchanting.

Now, it is making me nervous. Will the spirit of Thyme past survive the designer makeover, the Michelin-star ambition, and the £45 it costs for three courses. In short, will I love Thyme present as well?

Once through a small bar with seductive bordello lighting, the L-shaped dining-room is modern and comfortable in a corporate sort of way, lacking the surprise factor of a Heidi in plaits. With its big, round, double-clothed tables, huge padded armchairs, flecked carpet, lacquered wood carvings, and a slow curve of textured rear wall, it's a bit like dining in the foyer of a smart new hotel.

A battalion of nice young things bring slightly oily bread rolls and a plank of pre-dinner nibbles - good olives, crumbed squid, crisp pastries - before a pre-starter starter of a frothy little velouté of white onion and foie gras. It's lush and creamy, but thin on flavour.

Adam Oates has taken over the rest of the club's food and beverage requirements, while Adam Byatt is responsible for the restaurant menu, laid out as main ingredient headings followed by a brief description.

"Mullet", for example, is a crab-stuffed fillet of red mullet that has been moulded into a single baton, and served with baby fennel and a rust-coloured spoonful of sweet-and-sour red pepper mousseline that tastes intriguing. Not sure about the red mullet, though, as it ends up tasting neither of that lovely fish nor of crab.

Far better is "Shellfish", a generous platter of titbits of poached lobster, langoustine and seared scallops placed on delicate rolls of hand-made macaroni, scattered with fresh pea shoots and artful splodges of tarragon mayonnaise. Praise the Lord, at last some flavour - the shellfish sweet and sprightly, and the sea scallops so precisely cooked they have the texture of fruit jellies - all freshened up with the tiny green curlicues of the pea plant.

The wine list seems skewed towards the kind of people who can afford the £550-a-year plus £150 starting fee to join the club, with little worth looking at under £40. A rare exception is an Austrian Nittnaus Pinot Noir at £29, with fruit, finesse and balance.

Main courses tend to be bitsy affairs. "Duck" comes as a money-bag-shaped ravioli filled with minced leg accompanied by furls of caramelised breast, a seared little lobe of foie gras, a silky purée of sweet potato and a separate little cup of lavender consommé. The foie gras seems gratuitous and over-cooked, and the lavender in the broth adds little more than curiosity value, but the ravioli is richly ducky and the breast rare and tender.

So why am I not enjoying this? The food seems to lack sizzle and spontaneity, as if it has come up in a lift from room-service. Staff are sweet and caring, but nervous and tense, resulting in brain-dead mistakes and inconsistencies - particularly with wine service. At least Rooney's fiancée looks like she's having fun in her new incarnation.

"Pig" looks like a boy's-own treat with a nicely melting square of slow-cooked belly pork and a somewhat gooey, indistinct-tasting round of langoustine-stuffed trotter. I really have to question the point of adding crab to red mullet, lavender to duck consommé and now langoustine to trotter, however, if by combining disparate flavours like a mad genetic engineer, you lose the value of both. This is the most disappointing aspect of the new Thyme experience.

Desserts are well-executed, with "Chocolate" being three quenelles of gooey Valrhona chocolate emulsion, a lovely Frangelico ice cream and a random scattering of toffeed hazelnuts. Quality without theatrics.

Adam Byatt is still a bloody good cook and there are flashes that remind me why I scored the old Thyme 17. But I miss the delicacy and harmony of the old kitchen. In his defence, Byatt says it will take time to grow into his new surroundings, but I think the leap has been too great, and the team has lost its natural momentum.

In the move to the big time, they see to have forgotten to bring themselves with them.

14 Thyme The Hospital, 24 Endell Street, London WC2, tel: 020 7170 9200. Lunch and dinner Mon to Sat. Set-price dinner £45 per person for three courses, plus wine and service

Scores 1-9 Stay Home And Cook 10-11 Needs Help 12 Ok 13 Pleasant Enough 14 Good 15 Very Good 16 Capable Of Greatness 17 Special, Can't Wait To Go Back 18 Highly Honourable 19 Unique And Memorable 20 As Good As It Gets

Second helpings: More herbaceous restaurants

Lemongrass, 243 Royal College Street, London NW1, tel: 020 7284 1116
While this intimate Camden Town favourite draws on influences from all over south-east Asia, the main heat is on Cambodian and Thai - from old faves such as fishcakes, satays and spring rolls, to the esoteric steamed and fried leek cakes, whisky prawns and lok luk steak.

Mint, 47 Ranelagh, Dublin, tel: 00 353 (0)1 497 8655
This cosy (read small) dining-room on Ranelagh's trendy dining strip in the middle of Dublin opened late last year with some real skill in the kitchen. It shows in clever modern dishes such as sea bream with wild mushroom foam, confit chicken and ham hock terrine and a ballotine of fresh and smoked salmon.

Bay, Tree 4 Potter Street, Melbourne, Derbyshire, tel: 01332 863 358
The old world meets the new in this 200- year-old former coaching inn in a small market town eight miles south of Derby. It has a menu ranging from smoked haddock and vodka risotto and Thai fishcakes to Chinese "ants climbing trees" (relax, it's noodles with pork) and crispy Lunesdale duckling with a Saint Clements sauce.