The family was settled in Monmouthshire in the 13th century. The original form of the name, which was resumed by the dukes of Somerset from early in the 19th century to 1923, seems to have been St. Maur, of which William Camden says that Seymour was a later corruption. It appears that about the year 1240 Gilbert Marshal, Earl of Pembroke, assisted William St. Maur to wrest a place called Woundy (now Undy), near Caldicot in Monmouthshire, from the Welsh. Woundy and Penhow, at the latter of which he made his residence, were the property of Sir Richard St. Maur at the end of the 13th century, but they were lost by the family through the marriage of Sir Richard's great-great-granddaughter, the only child of John St. Maur, who died in 1359. John St. Maur's younger brother Roger married Cecily de Beauchamp (d.1393), one of the daughters and eventual co-heiresses of