It used to be claimed that Plymouth House was one of the surviving halls of residence from Illtud’s monastery. Its history does not go that far back but there is evidence that it may incorporate the remnants of a halled house of the fifteenth century. It was often referred to as the Great House and belonged to a branch of the Stradling family who purchased it along with the estate known as Abbot’s or West Llantwit at the time of the dissolution of the monasteries. When their line died out the property reverted to the maternal line. They were created Earls of Plymouth and it was only in the nineteenth century that the present name came into use.