In 1363 Nov 20, Maior, ballivi et probi homines was granted, by Edward III, (In year 37 of his reign) a Royal licence to crenellate Coventre (Coventry)

"Licence for the mayor, bailiffs, citizens and good men of Coventre to crenellate their city.(civitatem)"

Granted at Westminster, by privy seal.

Murage first granted 1329 but work probably didn't start until 1364. A licence to complete the work was issued in 1385. Circuit was only finally completed in 1540.

Original source is

• Calendar of Patent Rolls (1361-64) p417
  Calendar of Patent Rolls (1381-85) p557

(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;

• Stephens, W.B.(ed), 1969, 'The City of Coventry: Introduction' VCH Warwick Vol8 p1-23
  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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