The owners of long-established restaurants, as of newspapers, need to keep making changes to keep things fresh. A subtle redesign, some fashionable new ingredients, maybe even a shake-up of personnel. What they don't normally do is throw everything out but the name, and start again with completely new content.

That's just what Gordon Ramsay has done with his restaurant group's latest opening, the third to go by the name of Pétrus. After a schism with former protégé Marcus Wareing, head chef of the earlier incarnations of Pétrus, Ramsay took the bold – some might say vainglorious – decision to strip the Berkeley Hotel restaurant of that famous name, and use it for a rival new venture just down the road.

The new Pétrus, which opened last month, has plenty to prove. Ramsay's restaurant group has been buffeted by financial problems, closures and lost Michelin stars, while Ramsay himself continues cheffing and blinding his way around the world on TV. (Meanwhile, back at the Berkeley, Marcus Wareing and his two Michelin stars have somehow managed to struggle along regardless.) Taking no chances, Ramsay has deployed his crack troops at Pétrus, including manager Jean-Philippe Susilovic, the shellac-haired smoothie familiar as "JP" to viewers of Hell's Kitchen.

It's always a shock to experience the disjunction between Ramsay's ballsy TV persona and his restaurants, which epitomise chilly, knees-together fine-dining. This new Pétrus is smaller and friendlier than the Berkeley Hotel version, but only in the way that Nicolas Sarkozy is smaller and friendlier than Vladimir Putin.

The circular beige room, arranged around a central wine area, is expensively neutral, with elements of discreet bling; it isn't a hotel dining room, but it could be. One word you don't associate with Gordon Ramsay is bland, and this room feels bland, agreed my guests Frank and Di Eliel, the generous Independent readers who bid to accompany me on a review in our annual charity auction.

The offer of cannabis, from a Germanic waitress, seemed to offer the perfect ice-breaker, but it turned out she was introducing the canapés – fried fingers of polenta with tomato sauce, followed by an onion velouté. Nothing too interesting, but fairly characteristic of the Ramsay house style, which offers refined accomplishment over excitement.

All three of us were happy with most of what we tried from the three-course menu but the food didn't set our pulses racing. Di, who described herself, alarmingly, as "a watercress soup fiend", felt there was a lack of pepperiness to the vivid green liquid which was poured over roasted langoustine tails, to stunning visual effect. Also beautiful, but marginally underpowered, was Frank's tartar of yellow-fin tuna, sprinkled with Oscietra caviar. Veal sweetbreads came fried in breadcrumbs, their delicate flavour subsumed into something akin to a chicken nugget, though punchy choucroute rescued the dish from blandness.

The huge wine list bristles with famous French names, but Frank showed his sense of adventure by selecting a bottle of Malbec from Patagonia. It prompted memories of the Eliels' travels: they seem to have globe-trotted around most of the world, including Patagonia and the Falklands (twice) – though living as they do near Norwich, they obviously steer clear of Ipswich.

By the time we'd finished a bottle of Albarino and were getting stuck into the Malbec, we were getting along famously. So much so, that my notebook remains silent about the main courses, apart from recording the key facts that Di had pan-fried sea bream with an oyster velouté, and that Frank's roasted duck breast with confit leg, braised beetroot and ginger sauce was "fine". My memory of my own choice needs no jogging; the partnership of squeaky roast lobster tail with a flavourless lozenge of braised pork belly created a surf'n'turf combo of memorable pointlessness.

Side dishes, including pommes dauphinoise, arrive unbidden, and are left at the table to share. For a Ramsay joint, that's almost casual. In fact, the service does feel relatively relaxed, from a team who exhibit personality and knowledge rather than drone-like obedience. And the attentions of restaurant manager Jean-Philippe were most welcome, even though the Eliels claimed never to have seen him on Hell's Kitchen (probably too busy backpacking around Tristan da Cunha...).

Desserts showed a welcome flash of exuberance, in particular the star dish of the evening, a glossy chocolate sphere, which, anointed with hot chocolate sauce, imploded to reveal its cargo of ice-cream and honeycomb. Bitter chocolate beer parfait, foam-topped, like a genuine pint, contained nuggets of puffed rice which Di guessed might be Quakers.

Bombarded by waves of pre- and post-starters and offers of digestifs, we started to suspect we may have been identified, particularly when JP offered to take us downstairs to see the kitchen and meet executive chef Mark Askew and his team. But it seemed most diners were getting this red carpet treatment; at one point, there seemed to be more customers in the kitchen than in the dining room.

Whether or not we were outed, we left Pétrus feeling that we had experienced the special evening we'd hoped for. There may not be anything dazzling about the food, but the smoothness of the operation, and Ramsay's determination to make a success of it, make it the ideal venue for a special occasion. Ironically, given its shouty owner, Pétrus feels like a background restaurant, rather than one that grabs you by the lapels and starts showing off. That we ended up having such an enjoyable evening was down to the staff, the Patagonian Malbec, and above all, the company.

Pétrus, 1 Kinnerton Street, London SW1 (020-7592 1609)

Food 3 stars
Ambience 3 stars
Service 4 stars

£55 a head for three courses before wine and service

Tipping policy: "Service charge is 12.5 per cent discretionary, of which 100 per cent goes to the staff; all tips go to the staff"