the priory was founded by withenoc (or gwethenoc), a breton who became lord of monmouth in 1075. there is evidence in the book of llandaff of an earlier 8th century celtic church, and it has been tentatively suggested that this may have been on the site of the later priory. the priory was granted to the abbey of st florent at saumur, and was consecrated in 1101. the priory church was extended and became the parish church later in the twelfth century. the priory was dissolved in 1536.