It's not the restaurant, it's the beef.

I actually have a friend who's a beef farmer over here, and we've talked about this at length. There's no UK equivalent of the USDA grades of meat, and thus no incentive to selectively breed cows for flavor and quality.

You can go to a specialty butcher over here and get the absolute best steak they have, and it still won't be as tasty as the one you'll find on sale at any grocery store in the US.