Sir Isaac Greatorex belonged to a religious sect in the 18th century. The dismemberment of and subsequent bleeding of animals - especially dogs - was fundamental to their beliefs. It was widely-believed that Greatorex's devil-worship and witchcraft resulted in him being forced to leave Winterborne School and being hanged.
In the 20th century, Whittaker and Gavin Purcell revived the cult for fun. However, after inducting Christian Purcell into the cult, Christian claimed to be possessed by Greatorex and took charge. In 1995, he killed Whittaker and his dog Monty, as well as Barbara Taploe's dog Badger. He later killed Luke Pendrell and attempted to kill Andrew Powell in order to resurrect himself. He was stopped by Liz Shaw. (HOMEVID: The Devil of Winterborne)