In 1348 July 10, Abbas et Conventus de Whalleye (Abbot John Lindley) was granted, by Edward III, (In year 22 of his reign) a Royal licence to crenellate Whalleye (Whalley Abbey)

"Licence for the abbot and convent of Whalleye to crenellate their church and the close of the abbey. (ecclesiam suam et clausum Abbatiae suae)"

Granted at Westminster, by privy seal.

Building work began about 1320 and continued well into the C15. The large north-west Gatehouse (not crenellated) dates from before the licence. Expensive litigation restricted the funding available for new building, according to the VCH, shown by the long period of building. This litigation, with the Earl of Lancaster, would have increased Abbot John Lindley's contact with royal officials and possibly influenced a desire by the Abbot and Abbey to be show their status.

Original source is

• Calendar of Patent Rolls (1348-50) p124

(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. Licentia is best translated as 'freedom to' not 'permission'.)

Significant later source are;

• Coulson, C., 1982, 'Hierarchism in Conventual Crenellation' Medieval Archaeology Vol26 p94
  'Houses of Cistercian monks: The abbey of Whalley', A History of the County of Lancaster: Volume 2 (1908), pp. 131-139. URL: http://www.british-history.ac.uk/report.aspx?compid=38350. Date accessed: 15 April 2008
  Turner, T.H. and Parker, J.H., 1859, Some account of Domestic Architecture in England (Oxford) Vol3 pt2 p415

More details about licences to crenellate can be found here.

Please let me know if you see any errors, can add information or can otherwise help to improve this resource. Contact me