In 1340 Feb 4, Thomas de Blemansopp (Thomas de Blencansopp) was granted, by Edward III, (In year 14 of his reign) a Royal licence to crenellate Blemansopp in Marchi. Scociae [Blencansopp] (Blenkinsopp Castle)

"mansum suum de Blemansoppe in marchia Scocia"

Granted at Kennington, by letter of the Keeper.

This licence issued by the 'Custos Anglia' in the King's name at Kennington was repeated or ratified in May

Original source is

• Calendar of Patent Rolls (1338-40) p417

(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;

• Emery, Anthony, 1996, Greater Medieval Houses Vol1 (Cambridge) p159
  King, D.J.C., 1983, Castellarium Anglicanum (London: Kraus) Vol2 p366n67
  Bates, C.J., 1891, Border Holds of Northumberland (London and Newcastle: Andrew Reid) p9n40
  Turner, T.H. and Parker, J.H., 1859, Some account of Domestic Architecture in England (Oxford) Vol3 pt2 p412

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