In 1152 or 1153 Simon's son Simon II de Senlis, Earl of Huntingdon-Northampton gave Merton to the Knights Templar. In 1185 the manor covered seven hides, making it their largest estate in Oxfordshire. In 1312 Pope Clement V ordered the Templars' dissolution and their English estates were confiscated by Edward II, who granted Merton to the Knights Hospitaller in 1313. In 1540 the Hospitallers were suppressed in the Dissolution of the Monasteries and surrendered Merton to the Crown, which left it in the possession of the Templars' tenant, William Mablyston of Ludgershall, Buckinghamshire.