I've been to Britain several times to visit my wife's family members and relatives. I'd say a Brit restaurant might meet with success in the U.S. There's been two Brit restaurants that have opened (and failed) in my area. Unfortunately, both were located in small towns far from the main population center.
But dishes of roast beef and Yorkshire pudding, shepherds pie, bangers and mash, fish and chips, Cornish pasties, bubble and squeak (just kidding), might go over very well with a lot of Americans. It's almost impossible to beat the Brits for fish and chips. Just over there last May-June, and ate f & cs numerous times. Their standard f & c dinner is superior to around my area, western Wisconsin, and we're known for Friday fish fries in these parts.
I know many in the San Fran area would eagerly gobble up some of this...
Probably not better than Lake Erie wall-eye around Cleveland, betcha!