According to the blue plaque on the wall outside Plymouth House (), the house is believed to have been formerly part of the monastery, perhaps functioning as a halled house for some time in the fifteenth century. After its closure in 1539, it became the manor house of West Llantwit owned by Edward Stradling. Later owners include Lewis of the Van, the Earl of Plymouth and then Dr. J. W. Nicholl Carne, who renamed it after its previous owner some time in the 19th century.