Down a warren of streets in Shepherd Market, a corner of (mostly) bygone ill repute in Mayfair, the entrance to 5 Hertford Street is quiet from the outside. Then the door opens, attended not by burly guards, but by women in floor-length dresses, and you step into a residence of unusual charm. This is a grown-up club, where your parents and grandparents are as at home as your friends from school. There are roaring fires in nearly every room, a cigar shop, a handful of bars, and an arrestingly pretty restaurant where you can bring your dog along for lunch. The artwork is real and the drinks are cold. Loulou’s night club is downstairs for after dinner.