The priory was founded in 1142 as the Augustinian priory of Clack, and dedicated to St. Mary. It was well-sited on a high ridge near a holy well, with further springs nearby; there is some evidence that a chapel of the era of Henry I already existed at the holy well.
The founder, Walter FitzEdward (otherwise D'Everaux), was the son of Edward De Evreux of Salisbury, a High Sheriff of Wiltshire; he gave lands for a priory as a daughter house of St. Mary's Abbey, Cirencester, according to its charter, "to serve God forever!". After the death of his wife, he "took the tonsure and habit of the canons" and on his death in 1147, was buried in the Priory, near the choir. His descendants, the Earls of Salisbury remained closely connected with the priory for many years. In 1190 thirteen of the monks migrated to Cartmel Priory, Cumbria, which had been recently established by William Marshal.
Throughout most of its early history, the priory also enjoyed royal support, being granted a charter by Henry II some time between 1173 and 1179; Richard I also lent assistance for the priory to break away from the abbot of Cirencester to become a priory in its own right, and King John, a frequent visitor, intervened to confirm this secession.This tradition continued with the grant of royal protection by Henry III, who visited in 1235.
By the 14th century Bradenstoke Priory had gained wealth and lands in nine counties besides Wiltshire. The priory was dissolved on 17 January 1539 at the Dissolution of the Monasteries; at about this time, its total income was £270 10s 8d. It then passed from The Crown to a Richard Pexel (or Pecsall) and his heirs sold it to the Methuen family of Corsham.
John Aubrey described the priory as "Very well built, with good strong ribs", and having a cellar "the stateliest in Wiltshire". But he added "the very fundations of this fair church are now, 1666, digged up, where I saw severall freestone coffins ... and severall capitalls and bases of handsome Gothique pillars. On the west end of the hall was the King's lodgeings, which they say were very noble, and standing about 1588."
From Wikipedia