That's a tough one. I would have to say the Dorchester Hotel in London has a couple of incredible restaurants. There's lots of great places to eat in Vancouver, too. I love La Regalade for excellent French bistro food -- authentic atmosphere and everything is made from scratch with the best ingredients.
Tojo's sushi bar in Vancouver is one of the best in North America. Lots of celebs eat there and the sushi is out of this world. Expensive, but worth it.