In 1376 Dec 4, Willielmus de Kerdeston, miles (William de Kerdiston) was granted, by Edward III, (In year 50 of his reign) a Royal licence to crenellate Claxston (Claxton Castle)

"Licence for William, son of William de Kerdeston, knight, to finish the work of crenellating the dwelling house (mansum) of Claxston,co. Norfolk begun by his father with the king's licence; the father having died before the completion of the work. "

Granted at Havering manor, by privy seal.

This licence, this time to complete the work started by his his father, was obtained by William's bastard son, also called William. This may not imply caution on the part of William II but rather that he too wanted the status that a licence to crenellate conferred - particularly important given that he was illegitimate. Parker footnotes "This entry states that a licence had been granted to his father, but that the house was only commenced by him."

Original source is

• Calendar of Patent Rolls (1374-77) p395

(In fact, the original source given is usually a transcription/translation of what are precious medieval documents not readily availably. It should be noted that these transcription/translations often date to the nineteenth or early twentieth centuries and that unwitting bias of transcribers may affect the translation. Care should also be taken to avoid giving modern meaning to the medieval use of certain stock words and terms.)

Significant later source are;

• Liddiard, R., 2000, Landscapes of Lordship (Oxford: BAR 309) p117
  King, D.J.C., 1983, Castellarium Anglicanum (London: Kraus) Vol2 p312n6
  Turner, T.H. and Parker, J.H., 1859, Some account of Domestic Architecture in England (Oxford) Vol3 pt2 p417

More details about licences to crenellate can be found here.

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