The Victorian era saw a rising public interest in psychic phenomena such as seances, ghosts and communication with spirits. Spiritualism was a fast growing belief system between 1840 and 1920, combining Christianity with a belief in the spirit world and the possibility of contacting ghosts through mediums. Classic ghost stories written in this period include A Christmas Carol, by Charles Dickens; The Canterville Ghost by Oscar Wilde and The Turn of the Screw by Henry James.
Unscrupulous pretenders took advantage of superstition by posing as mediums, offering exorcisms and hosting seances. 1876 saw the famous trial of Henry Slade, who had practiced as a medium in England and America. He was found guilty of fraud and sentenced to three months of hard labour.
Sarah Water's novel Affinity (2000) explores the world of Victorian spiritualism and its potential for deception.
On page 138, Herr M explains why he can only summon female ghosts, referring fleetingly to a lost lover in a 'kingdom by the sea'. His words reference Edgar Allan Poe's poem Annabel Lee (1849). The poem tells the tale of a lost love from the point of view of her bereaved lover. It suggests that the angels, jealous of the couple's happiness, took Annabel away but that she lives on in her lover's dreams, as he sleeps by the side of her tomb.