In 1343 Aug 21, Johannes de Norwico (Sir John de Norwyc) was granted, by Edward III, (In year 17 of his reign) a Royal licence to crenellate Lyng (Lyng Hall, Wood Norton)

"Licence for John de Norwico to crenellate the dwelling-places of his manors (mansum manerii) of Metyngham, co. Suffolk, and Blakworth and Lyng, co. Norfolk."

Granted at Westminster, by privy seal.

Licence to crenellate granted to Sir John Norwich in 1343 for Blakworth, Lyng and Metyngham

Original source is

• Calendar of Patent Rolls (1343-45) p106

(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) p108
  Emery, Anthony, 2000, Greater Medieval Houses Vol2 (Cambridge) p166
  King, D.J.C., 1983, Castellarium Anglicanum (London: Kraus) Vol2 p313n24
  Turner, T.H. and Parker, J.H., 1859, Some account of Domestic Architecture in England (Oxford) Vol3 pt2 p413

More details about licences to crenellate can be found here.

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