Many sources credit Augustus Elliot Fuller, MP (1777 - 1857) a keen huntsman and sportsman, with originating the Sussex Spaniel breed. They say he kept the breed for 50 years. Other sources say a," Mr Fuller of Rose hill" started the breed in 1795. This is confusing because A. E. Fuller inherited Rosehill, Brightling upon the death of John "Mad Jack" Fuller in 1834. Perhaps A. E. Fuller kept Sussex Spaniels before he inherited Rosehill. I have no evidence that Jack Fuller kept Sussex Spaniels.
A. E. Fuller was the son of John Trayton Fuller (c. 1743 - 1811) and Anne Elliot (1754 - 1835) of Ashdown House, Forest Row (now a school). John Trayton Fuller's father Thomas Fuller (1715 - 1780) and John "Mad Jack" Fuller's father Henry Fuller (1713 - 1761) were brothers.