Roux at Parliament Square RICS, Parliament Square, London SW1

There are tough times ahead, but Roux at Parliament Square is more classy coalition than culinary compromise

Since 1993, Michel Roux Jr has been successfully running the world-famous Le Gavroche in Mayfair. He has never been an empire builder like Marco Pierre White or Gordon Ramsay and, as a result, you could always depend on him being in the kitchen on Upper Brook Street.

Now, it seems, he has become ambitious. Not only has he opened a new restaurant, but he's named it after himself – or, at least, his family. He's also taken a risk with the food, which is poised uneasily between old and new. This is a departure from the French classical cuisine the Roux family is famous for. Outside of Paris, there are few practitioners in this tradition as celebrated as Michel Jr and his brother Alain, who now runs The Waterside Inn at Bray.

To add to the risk, Michel Jr has opened his first colonial outpost on the corner of Parliament Square. Not a particularly wise choice given the new Government's emphasis on frugality. All ministers have been forced to take a five per cent pay cut while senior civil servants are having a pay review. Who will be able to afford to dine at this smart new restaurant?

As if this didn't make the enterprise perilous enough, there's the fact that it's located in the building of the Royal Institute of Chartered Surveyors. Are there five words in the English language more guaranteed to bring a yawn to a person's face? Short of hiring Steve Davis as the maître d', it's hard to know how you could make the restaurant more boring. Does Michel Jr have a death wish?

I arrive at 1.30pm on Monday. There is a suitably grand entranceway, as you would expect from a Royal Institute, with a sweeping staircase, but the colour scheme is peculiar: the floor is covered in grey carpet and the theme in the main dining-room is gold and maroon. Very different to the haute bourgeois Gavroche.

I am shown to a table in the private dining-room, where my four guests are waiting, and handed a complimentary glass of champagne. Things are looking up. Michel Jr then appears to explain that he won't be there that afternoon. Instead, we'll be in the capable hands of Daniel Cox in the kitchen; Michel has no intention of giving up his day job at Le Gavroche.

If you choose three courses from the à la carte menu, the price is £55, but there's a three-course lunch menu for £29.50, so we all opt for that. For a meal bearing the Roux brand, that's pretty good value. The first thing to appear from the kitchen are some amuse-bouches, including a square onion crisp topped with anchovy and a little doughnut stuffed with foie gras. These are both melt-in-your-mouth good, the sort of nibbles that would have you scanning the room for girls holding trays at a cocktail party.

For my starter, I choose chicken liver and foie-gras parfait with poached rhubarb and two plump slices of toasted brioche. The combination of the silky smooth parfait with the crunch of the toast is exquisite and the tartness of the rhubarb perfectly offsets the creamy richness of the foie gras.

The most enticing main course on the set menu is roast sea bream, but alas that is off today, so I go for Berkshire Black pork belly accompanied by heritage carrots, Pommery mousseline and some creamed potato. This is perfectly executed and the pork has a deep, pungent flavour. I particularly like the little metal jug of jus that is set beside my plate, enabling me to create little pools of deliciousness in my creamed potato. My neighbour, who has plumped for sea trout, is equally happy judging from her little moans of pleasure.

In between our mains and our puddings we are served a strawberry sorbet and strawberry panna cotta, topped with a meringue triangle, which is a show-stopper. Why isn't this one of the dessert options? In the event, the warm chocolate brownie with marshmallow and caramel ice-cream doesn't disappoint. This is just the kind of sugar hit you crave after a meal as rich and overpowering as this.

Will Roux at Parliament Square overcome the various challenges ranged against it? My conclusion is that it will, thanks to the talent of newcomer Daniel Cox. People will flock from miles around for food of this quality. He may not be a Roux, but he is a worthy standard-bearer of the family's illustrious flag.

Roux at Parliament Square RICS, Parliament Square, London SW1, tel: 020 7334 3737

17/20

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

Lunch and dinner, Mon-Fri; dinner, Sat. About £70 for lunch for two without wine

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Reviews extracted from 'Harden's London and UK Restaurant Guides 2010'. www.hardens.com