The Gatehouse website record of a licence to crenellate for St Andrews Priory, Rochester granted on 1344 April 22

Grant in frank almoin, after inquisition ad quod damnum taken by John de Cobeham, constable of the castle of Rochester, to the prior and convent of Rochester of the king's dyke without the wall of the city of Rochester, leading from the east gate towards Canterbury, as far as the gate of the prior towards the south, for them to fill the same in with dung and earth and make their profit thereof; on condition that they make on their own soil a new wall of stone sufficiently crenellated, of the height of 16 feet, without the dyke aforesaid and a new dyke corresponding to the old one, to wit 54 perches, 14 and half feet, long and 5 perches, 5 feet, broad, to be maintained for ever at their charges. By p.s. (CPR)

Si concedamus, &c. Priori et Conventui Roff. fossatum nostrum extra murum civitatis Roff. qui se extendit a porta orientali ejusdem civitatis versus Cantuar. usque portam dicti Prioris versus austrum, &c. ita quod iidem Prior et Conventus fossatum illud firmis et terra implere, &c. et quod loco ejusdem muri unum novum murum de petra sufficienter kernellatum altitudinis sexdecim pedum extra dictum fossatum et unum novum fossatum extra eundem murum sic de novo faciend. in solo ipsorum Prioris et Conventus ibidem in longitudine et latitudine competens faciant suis sumptibus, &c. manutenend., &c. dictum fossatum sic implend. continet in se quinquaginta et quatnor particatas et quayuordecim pedes terrae et dimid. in longitudine et quinque particatas et quinque pedes terrae in latitudine, &c. (Turner and Parker)

Original source is;

Lyte, H.C. Maxwell (ed), 1902, Calendar of Patent Rolls (1343-45) p. 262 online copy

(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. Licentia is best translated as 'freedom to' not 'permission'.)

Significant later sources are;

Coulson, Charles, 2007-8, 'On Crenellating, in Kent and Beyond - A Retrospection' The Castle Studies Group Journal Vol. 21 p. 189-201 esp p. 196
Coulson, C., 1994, 'Freedom to Crenellate by Licence - An Historiographical Revision' Nottingham Medieval Studies Vol. 38 p. 92n18
Page, Wm (ed), 1926, 'Houses of Benedictine monks: The cathedral priory of St Andrew, Rochester' VCH Kent Vol. 2 p. 121-26
Turner, T.H. and Parker, J.H., 1859, Some account of Domestic Architecture in England (Oxford) Vol. 3 part 2 p. 414 online copy

More information about licences to crenellate can be found here.

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