The thing about the Boisdale on Bishopsgate is it's very discreet. You duck down a little alleyway into a comforable bar and go downstairs to the softly lit cellar restaurant. The staff are friendly and the whole place has a sort of posh-but-ordinary atmosphere like a cross between a posh restraurant and a gastro-pub. It's a very chilled, anonymous place where you can get hammered with really good food. It's not so flash it's for special occasions only but it's also special enough for a birthday or anniversary.
The menu is Scottish produce done in a simple, French style. It's all kinds of fish, game, cheese, fruits, seafood and steaks. The wines are great but not cheap and it's got the largest selection of whiskies in London, but be warned some of them actually cost more than your dinner per glass. You're better off nipping upstairs for a cheeky pint or two afterwards.