In 1367 Oct 20, Abbatissa et Conventus Shafton was granted, by Edward III, (In year 41 of his reign) a Royal licence to crenellate Shafton (Shaftesbury Abbey)

"Licence for the abbess and convent of Shaftesbury to crenellate their church and belfry (ecclesiam abbatiae et campanile ejusdem)"

Granted at Westminster, by King.

A complaint was made by the abbess and the king's tenants of Shaftesbury in 1341 that many evil-doers and breakers of the peace were going about armed, robbing and killing their servants, and that no remedy had been provided hitherto.

Original source is

• Calendar of Patent Rolls (1367-70) p10

(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 p94
  Page, Wm (ed), 1908, 'House of Benedictine nuns: The abbey of Shaftesbury' VCH Dorset Vol2 p73-9
  Turner, T.H. and Parker, J.H., 1859, Some account of Domestic Architecture in England (Oxford) Vol3 pt2 p416

More details about licences to crenellate can be found here.

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