What about the WhiteStar line of London Restaurants (by Marco Pierre White)? There are 8 of them, all very high end. In fact, most people wouldn't even recognize them as being part of a 'chain'. They include:

Belvedere, Criterion, Drones, L'Escargot, Mirabelle, and Quo Vadis.

See: http://www.whitestarline.org.uk/

I've eaten at the Picasso Room @ L'Escargot, where they have real Picasso paintings. It was a magical evening.