Dr Samuel Holywell was a physician in 18th century London who possessed latent psychic powers. He was interested in the arcane and occult. He collected unusual objects, studied magic and held séances in which he made contact with what he believed were the spirits of the dead.
The Fifth Doctor investigated his claims and discovered that the "spirits" were actually the collective unconsciousness of Carthok's victims. After aiding in the rescue of Quincy Flowers and defeat of Carthok, Holywell was made a member of the Diabola Club in gratitude. (AUDIO: Phantasmagoria)