From an online biographical entry of his son, Sir A.Conan Doyle :
When his son Kingsley died from wounds incurred in World War I, the author dedicated himself in spiritualistic studies. An example of these is THE COMING OF FAIRIES (1922). But he had already showed interest in occult fantasy before publishing Holmes stories. In his early novel, THE MYSTERY OF CLOOMBER (1888), a retired general finds himself under assault by Indian magic.
Doyle supported the existence of “little people” and spent more than a million dollars on their cause. The so-called “fairy photographs” caused an international sensation when Doyle published a favorable account of them in 1920. The photographs showed fairies dancing in the air. A year after, the Star newspaper reported that the fairies were from a poster. Doyle became president of several important spiritualist organizations. In 1925 he opened the Psychic Bookshop in London. Among his friends was the legendary American magician and escape artist Harry Houdini (1874-1926). He believed that Houdini possessed supernatural powers, which the magician himself denied. Another friend was D.D. Home. According to Doyle, he could levitate. Once Doyle claimed that Home “floated out of the bedroom and into the sitting room window, passing seventy feet above the street.” His own psychic experiences Doyle recorded in THE EDGE OF UNKNOWN (1930), which was his last book. Doyle died on July 7, 1930 from heart disease at his home, Windlesham, Sussex.
“My contention is that Sherlock Holmes is literature on a humble but not ignoble level, whereas the mystery writers most in vogue now are not. The old stories are literature, not because of the conjuring tricks and the puzzles, not because of the lively melodrama, which they have in common with many other detective stories, but the virtue of imagination and style. They are fairy-tales, as Conan Doyle intimated in his preface to his last collection, and they are among the most amusing of fairy-tales and not among the least distinguished.” (Edmund Wilson in Classics and Commercials, 1950)
From a brief summary of C.A. Doyle’s life:
In 1876 Charles was dismissed from his job [as an architect- ETat] at the Office of Works and put on a pension. Later that year he was sent to Fordoun House, a nursing home that specialized in the treatment of alcoholics.
While Charles was originally sent to Fordoun House because of his alcoholism he later developed epilepsy. At the time there was no known treatment and the condition was widely misunderstood. Sadly, his epilepsy doomed him to a life of confinement.
In 1885 Charles tried to escape from Fordoun House. He became violent during the attempt and was sent to the Montrose Royal Lunatic Asylum until early 1892. From there he was transferred to the Edinburgh Royal Infirmary and finally to the Crighton Royal Institution. In 1893 Charles Altamont Doyle died.
To see the fairies that Charles Altamont saw, look here
For bibliography of published material and short overview – look here. [The illustration, watercolor 'The Eavesdroppers", is published there. I've no intention of commercial use - hope the proprietors won't mind my reference]