Philip de Barry founded the priory of St. Thomas à Becket at Ballybeg for the Canons Regular of St. Augustine in 1229. His grandson, David Óg de Barry, enlarged the revenues of the priory in 1251. Ballybeg was an extensive foundation, the priory church measuring some feet ( m) in length and feet ( m) in width. The cloister, situated on the south side of the church was feet ( m) square.