Well-Schooled in Murder by Elizabeth George

 He felt distinctly uncomfortable and wished for the first time that he had thought far enough ahead to bring Sergeant Havers.  Her working-class background and sartorial nonchalance would have eased them through the superficial difficulties created by his own blasted upper-crust accent and his Savile Row clothes.                                                                                                                                                         -- Elizabeth George, Well-Schooled in Murder (Bantam, 1990)

I've never been particularly fond of Agatha Christie's novels (too formulaic) but I find Elizabeth Geroge's novel full of detailed characters, psychological insight and complex plotting, more like P.D. James and Ruth Rendell, two British mystery writers I do like.  Elizabeth George is American, however, and brings an outsider's view to the class differences of English life, exemplified by upper-class Thomas Lynley of Scotland Yard and his working-class partner Barbara Havers.  In  Well-Schooled in Murder they are investigating the murder of a scholarship student at a public, i.e., private, school in West Sussex, a co-ed school full of competitive students and ambitious faculty, as well as a headmaster who is most concerned with avoiding scandals and keeping wealthy donors happy.  So far, so routine, but George takes the time to create a significant number of interesting characters among the students, the parents, the staff and the teachers, all of whom have their personal and significant peccadillos that in many cases contributed, directly and indirectly, to the murder and which George limns with precision and style.