Almost from the moment she set foot in New York more than 50 years ago, Fran Lebowitz has been part of the city’s social firmament. Like it, she has moved inexorably upmarket since she first made her name as a humorist in the 70s with a column in Andy Warhol’s Interview magazine. Back then, she hung out with the likes of photographer Robert Mapplethorpe and the New York Dolls as well as jazz...