A grave mistake - Ngaio Marsh

There will always be an England, and in the world of traditional crime fiction, there will always be an Upper Quintern, the sort of Little English Village that is home mostly to the very rich and the servants who make their lives delightful. But Sybil Foster's life is not delightful, even if she does have an extremely talented gardener. Exhausted from her various family stresses - a daughter, for instance, who wants to marry a man without a title! - Sybil takes herself off to a local hotel that specializes in soothing shattered nerves. When she's killed, Inspector Alleyn has a real puzzler on his hands: Yes, she was silly, snobbish, and irritating. But if that were enough motive for murder, half of England would be six feet under.