Boxgrove Priory, in the village of Boxgrove in Sussex, was founded in about 1066 by Robert de Haye, who in 1105 bestowed the church of St. Mary of Boxgrove upon the Benedictine Abbey of Lessay. In about 1126 upon the marriage of Robert's daughter Cecily, to Roger St. John the number of monks living at Boxgrove was increased from the original three to six, and by 1187 there were a total of fifteen. The nineteenth monk was added to the priory in about 1230 by William de Kainesham, Canon of Chichester. By 1535 the priory's possessions were worth £185 19s. 8d. gross, and £145 10s. 2½d.