Gavin Alan Purcell was the headmaster of the Winterborne School. Like his predecessor, Wittaker, Purcell was fascinated by Isaac Greatorex who had founded the school in 1764. Greatorex had been an occultist who was ultimately executed for his gruesome witchcraft. Purcell and Wittaker revived many of Greatorex's rituals and convinced Purcell's nephew — Christian Purcell — that he was the reincarnated spirit of Isaac Greatorex. Christian grew into the role convincingly, and may even have been possessed by the evil spirit, to the extent that the older men began to take orders from him. Doubting Wittaker's commitment, Purcell helped Christian in the murder of the retired teacher, and attempted to cover-up Christian's ritualistic killing of two dogs. When Christian murdered his school friend Luke, Purcell took the blame to protect his leader. As Christian's murder spree continued, it became obvious that Purcell was not the the cult's mastermind. He broke down before Liz Shaw and begged forgiveness for turning his nephew into an insane monster, and tried to talk him out of murdering Andrew Powell. Christian vanished. (HOMEVID: The Devil of Winterborne)
Some months later, Christian's body appeared and Gavin Purcell was released from prison due to lack of evidence. Almost immediately, Andrew Powell began to be haunted by the ghost of Christian — in truth, the spirit of Greatorex — compelling him to resume the ritual murders and complete his resurrection. Andrew killed one of his fellow students but vanished when interrupted by the returning Purcell. Using Purcell's knowledge of the evil rituals, he, Liz and new school head Ms Wyndham summoned the evil spirit. Appearing first as Christian, he possessed the body of Purcell but was finally destroyed by Liz, reducing Purcell to a dessicated husk. (HOMEVID: Ghosts of Winterborne)