Wareing is often described as Ramsay's protege - indeed, he featured in several key scenes in the recent fly-in-the-soup TV series, lounging supportively in the background while Gordon fretted about whether he was going to win his third Michelin star. The friendship between the two chefs has improbably survived two stints in the same kitchen, first at Le Gavroche, then Aubergine, where Wareing worked as Ramsay's second before moving on to L'Oranger to establish a reputation as one of Britain's most promising young chefs, and winning a Michelin star. It was his dismissal from L'Oranger which prompted the walk-out of staff from sister restaurant Aubergine.
Now, Wareing has set up on his own, just up the road from his last employer, and has his sights fixed on retaining his star and eventually adding a second. Petrus had already been open for a month when I called to make a booking, but the Aubergine effect doesn't yet seem to have taken hold; I was surprised to be able to secure a Friday dinner table for the same week.
The frontage was still under scaffolding on the night of our visit, which my companion Allan, a professional foodie, thought a bit shoddy - generally he prefers his restaurants off the bone. But the interior has the hushed, expensive atmosphere you'd expect of an establishment in the heart of gentlemen's clubland. The design is unshowy and restrained, with outsize still-lifes, burgundy upholstery, and walls and carpet the colour of a rich mushroom veloute. Tables are well-spaced, so it's theoretically possible to have an intimate tete-a-tete, though in practice the attentiveness of the all-French waiting team meant that we were unable to get a clear run at a conversation for at least 20 minutes after sitting down.
The first pleasant surprise is the all-in pricing system - three courses cost pounds 28 (lunch is pounds 19.50) and there are no supplements. The menu is in English, but the cooking is modern French, with an emphasis on lighter ingredients and seasonal produce. The wine list - as you'd expect from a restaurant named after a great Bordeaux - is mainly French, and expensive, although the sommelier tactfully downscaled his suggestions until he'd reached our level with a pounds 34 bottle of Crozes-Hermitage.
We began with palate-freshening cups of cold pea soup, light but intensely flavoured, which we sipped from the kind of teeny spoons that Keith Richard might once have hung round his neck. My companion was ravished by his starter of sweetbread ravioli, a soft bundle of home-made pasta enfolding a melting filling of sweetbread, chicken farce and wild mushrooms, served with salsify and baby spinach. My pan-fried red mullet with aubergine caviare delivered powerful flavours with the lightest of touches, the natural robustness of the fish tempered by an emollient bed of creamed peas and broad beans. Both dishes were finished with a tracery of intensely reduced sauce, sticky and savoury as Marmite.
After starting with fish, I had intended to move on to venison, but was warned off - quite sternly - by Christophe, the maitre d', because both dishes were served with peas. So Allan claimed the venison, and I settled for roasted sea bass with oysters. I was very glad I'd done so. The fish was perfectly cooked, its scored skin astonishingly crisp and savoury, and plump, poached oysters lent a hint of their brine to a creamy sauce, flecked with tomato and chives.
Allan's roast loin of venison was less revelatory - the meat was well-coloured and tender, and a fricassee of peas and girolles worked well, but he felt there was something muted in the result, with too much of the punch coming from an intensely reduced jus. Presentation of both dishes was Michelin-pleasingly elaborate. There were other touches which should endear the restaurant to the inspectors - my companion approvingly identified the steak knives as Lagoule design classics.
There was no dilemma about whether to have puddings - the set-price menu means you're already paying for them, so you might as well indulge. I chose a vanilla cheesecake with a warm compote of rhubarb, one of the day's specials. The delicate confection that arrived bore little relation to its chunky homespun namesake, its tiny biscuit base delivering the whole cheesecake message in one bite-size morsel. Allan was persuaded to try an Earl Grey tea cream, and immediately regretted it, pronouncing the result "teabag pannacotta". But he soon developed a taste for its extraordinary, slippery texture and slightly medicinal taste, and warmly commended it to Christophe as "upmarket invalid's food", a judgement I suspected he probably wouldn't rush down to the kitchen to share with chef.
After an exhaustive analysis of the cheeseboard, I managed to bundle my companion out, though he was almost sidetracked by a last-minute offer to tour the wine store. From our vantage point next to it, however, we had already glimpsed the restaurant's reserve of vintage Chateau Petrus, which includes a 1945 listed at pounds 11,000. Unless you succumb to a moment of madness and order it, you can expect to pay around pounds 60 a head, although if you went at lunchtime and were disciplined about drink, you could have a great meal prepared by a first-class chef for half that amount. And that really is something worth shouting about. All right, Gordon? Petrus, 33 St James's Street, London SW1 (0171-930 4272). Lunch Mon- Fri 12-2.45pm. Dinner Mon-Sat 6.45-11pm. All cards. Limited disabled access. More leading wine lists: Bites, page 44