In the mid fourteenth century the castle was in the possession of the family of Monthermer. Ralph de Monthermer, Earl of Glouster, married Joan of Acres, sister of Edward II, by whom he had two sons, Thomas and Edward. The castle is said to have been built, as is more likely, a licence granted by the Crown to "Crenelate" the existing Manor c. 1340. (Butchart 1954)

No mention of this in VCH. Not in the rolls. Butchart appears to have assumed a licence was granted, presumably because of the mis-belief that such a licence was a requirement. Other authors have repeated this assertion without, apparently, ever checking it. Although this is the sort of house granted a licence and Edward Monthermer may well have wanted a licence to show he was back on good terms with the king this supposed licence is rejected on the grounds of no supporting evidence and by analogue with the large majority of such houses which were built without such a licence.

Edward de Monthermer died, without male issue, in February 1340, his brother Thomas died later the same year and the barony became extinct. Margaret widow of Thomas Monthermer held Warblington in dower till her death in May, 1349