In 1292 May 3, Willielmus de Grandisono (William de Grandison) was granted, by Edward I, (In year 20 of his reign) a Royal licence to crenellate Asperton (Ashperton Castle)

"Licence for William de Grandisono to strengthen his house (mansum) of Asperton co. Hereford, with a wall of stone and lime and to crenellate it."

Granted at Bury St. Edmunds,

Original source is

• Calendar of Patent Rolls (1281-92) p490

(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;

• King, D.J.C., 1983, Castellarium Anglicanum (London: Kraus) Vol1 p215n1
  Turner, T.H. and Parker, J.H., 1859, Some account of Domestic Architecture in England (Oxford) Vol3 pt2 p403

More details about licences to crenellate can be found here.

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