L'Atelier de Joel Robuchon, London

The opening of L'Atelier de Joel Robuchon has had the UK food scene's knickers in a twist. Mentioned on the BBC news, every food forum gasping for photos, reservations hard to come by. Is it worth it?

Having chosen to eat at Robuchon at the Mansion in Vegas earlier this year over their branch of L'Atelier, I was excited to try the less formal experience. So, having had a great day at work I deserved a glass of pink champagne and anticipating a tough day the next, I needed mash potato. Specifically, I needed Robuchon's mash potato, a dish close to my heart, being 50% butter and 50% potato. Listen carefully and you'll hear the sound of my arteries hardening for the rest of this report.

So what does L'Atelier bring to the London dining scene? Well, it's good to see a high-end restaurant that isn't owned by Gordon Ramsey, great to see a place where you don't need a reservation and excellent to see a room that's buzzing, rather than a cathedral to gastronomy.

The menu is extensive and roughly split into portions of three different sizes; tapas, starter and main. Sadly the bucket of mash didn't seem to be on that night, so I satisfied myself with "Tomate", "Palourdes", "Noix de Saint Jaques" and "La Caille" (served with mash). Things didn't get off to a good start. "Tomate" is gazpacho, but imagine peppery, watered-down supermarket ketchup and you get the idea. It was left after two mouthfuls. The clams were sent back, seeing as they had been cooked for about 45 minutes too long. I was starting to wonder what the Chef of the Century was up to. But then things got interesting...There was a huge apology and then "Langoustine" arrived. One lone, perfect langoustine, wrapped in the lightest pastry and fried. Things were looking up. Next, while they were sorting out the clams, the most beautiful mackerel tarte. Imagine the lightest filo pastry, topped with a tomato concasse and layered with sashimi thin mackerel, just warmed by the pastry. Add some parmesan and olives and you have a dish that's the perfect expression of umami.

"Noix de Saint Jacques" is a single scallop with citrus butter and seaweed flecks. But at £9 you could start to wonder about the quantity to quality ratio. I only ever worry about the cost of food when it's cheap and this was a very good scallop, cooked perfectly and just quivering in the centre. So I shan't complain. The clams re-appeared, much plumper, but no more than the sum of their parts.

And then the mash came. I'll gloss over the quail (although it's very good, especially the breast piece, stuffed with foie gras) and get to the point. This is the best mash potato you will ever eat. I think that a look of rapture must have spread across my face because the chap who was milling around behind the counter (who I was told was Robouchon, but I'm not sure) came over to chat. He took my critisism that the truffles were really sub-par and added nothing to the dish well. And then brought me over a small le creuset dish of the stuff. It might have been to shut me up (my French is schoolgirl level these days and my accent horrid) but I like to think that he just knows another mash potato fiend when he sees one. So I just sat there, spooning this glossy, creamy, unctuous puree into my mouth and thinking of a variety of uses for it. None of them publishable here.