She worked for the BBC and the UNIC, before she started writing professionally, mainly children's books and thrillers. For her books she received the Guardian Award (1969) and the Edgar Allan Poe Award (1972).
Many of her most popular books, including the Wolves Chronicles, were set in an elaborate alternate history of Britain in which James II is never deposed in the Glorious Revolution, but supporters of the House of Hanover continually agitate against the monarchy. These books also toy with the geography of London, adding a Canal District among other features.
Her series of children's books about Arabel and Mortimer are illustrated by Quentin Blake. Others are illustrated by Jan Pieńkowski.
Her many novels for adults include several that continue or complement novels by Jane Austen. These include Mansfield Revisited and Jane Fairfax.
Aiken was a lifelong fan of ghost stories. Her favourite authors were M. R. James, Fitz James O'Brien and Nugent Barker. She set her adult supernatural novel The Haunting of Lamb House at Lamb House in Rye (now a National Trust property). This ghost story recounts in fictional form an alleged haunting experienced by two former residents of the house, Henry James and E. F. Benson, both of whom also wrote ghost stories. Aiken's father, Conrad Aiken, also authored a small number of notable ghost stories.
Joan Aiken's Books on Amazon: Joan Aiken