In 1377 March 28, Abbas et Conventus Abbatiae Scoe. Werburgae [Sancte Warburgae] was granted, by Edward III, (In year 51 of his reign) a Royal licence to crenellate Abbatiae Scoe. Werburgae [Sancte Warburgae] (Abbey of St Werburgh)

"Licence for the abbot and convent of St. Werburgh's, Chester, to crenellate their abbey. (abbatiam)"

Granted at Westminster, by privy seal.

The abbey paid half a mark for a confirmation of the licence 8 months later (7 Nov 1377) after Edward's death.

Original source is

• Calendar of Patent Rolls (1374-77) p442

(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;

• Coulson, C., 1982, 'Hierarchism in Conventual Crenellation' Medieval Archaeology Vol26 p95
  Turner, T.H. and Parker, J.H., 1859, Some account of Domestic Architecture in England (Oxford) Vol3 pt2 p218, 417

More details about licences to crenellate can be found here.

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