Leslie Poles Hartley CBE (30 December 1895 – 13 December 1972), known as L. P. Hartley, was a British novelist and short story writer. His best-known novels are the Eustace and Hilda trilogy (1947) and The Go-Between (1953). The latter was made into a 1971 film, directed by Joseph Losey with a star cast, in an adaptation by Harold Pinter. Its opening sentence, "The past is a foreign country: they do things differently there", has become almost proverbial. His 1957 novel The Hireling was made into a critically acclaimed film of the same title in 1973.

He is also a noted writer of short fiction that has been acclaimed for its eerie, strange qualities that have drawn comparison with the macabre wit of Saki and the supernatural fiction of Henry James and Walter de la Mare.

The three books gathered together as Eustace and Hilda explore a brother and sister's lifelong relationship. Hilda, the older child, is both self-sacrificing and domineering, as puritanical as she is gorgeous; Eustace is a gentle, dreamy, pleasure-loving boy: the two siblings could hardly be more different, but they are also deeply devoted. And yet as Eustace and Hilda grow up and seek to go their separate ways in a world of power and position, money and love, their relationship is marked by increasing pain.

L. P. Hartley's much-loved novel, the magnum opus of one of twentieth-century England's best writers, is a complex and spellbinding work: a comedy of upper-class manners; a study in the subtlest nuances of feeling; a poignant reckoning with the ironies of character and fate. Above all, it is about two people who cannot live together or apart, about the ties that bind—and break.