The Gatehouse website record of a licence to crenellate for Allington Castle granted on 1281 May 23

Edwardus dei gracia Rex Angl' Dominus Hibern & Dux Aquitanni Omnibus ad quod praesentes littere prevenerint salutem. Sciatis quod concessimus pro nobis & heredibus nostris dilecto & fideli nostro Stephano de Penecestre & margarete uxor ejus quod domum suam de Alniton' in Comitatu Kantie muro de petra & calce firmare & kernellare & eadam sic firmatam & kernellatam tenere possint sibi & heredibus suis imperpetuum sine occasione vel impedimento nostri vel heredum nostrorum aut ministrorum nostrorum quorumcunque. In cujus rei testimonium has literas nostras fieri fecimus patentes. Teste me ipso apud Westm' vicesimo tertio die maij anno regni nostri nono.
(This is my transcriptions of the National Archives original. I have attempted to expand the abbreviations used in that but I am not a Latin scholar, although the formulaic nature of royal grants make such a transcription relatively straight forward. If an accurate transcription is required reference should be made to the original. Philip Davis 19-4-2010)

Edward by the grace of God King of England, Lord of Ireland and Duke of Aquitaine, to all to whom these letters come, greetings.
Know that we have granted on behalf of ourselves and our heirs that our beloved and faithful Stephen of Penchester and Margaret his wife that they may fortify and crenellate their house at Allington in the county of Kent with a wall of stone and lime, and that they and their heirs may hold it, thus fortified and crenellated, for ever, without let or hinderance of us or our heirs or any of our officials. In witness whereof we have caused these our letters to be made patent.
Witnessed by myself at Westminster on the twenty-third day of May in the ninth year of our reign.
Signed and sealed by Edward I (Godwin)

Licence for Stephen de Penecestre and Margaret his wife to crenellate their house of Alinton, co. Kent. (CPR)

Stephanus de Penecestre et Margareta uxor ejus ... domum ... Alinton, Kanc. (Turner and Parker)

Original source is;

National Archives E329/470 - Either the original patent letter or a copy with exceptionally fine seal. This is not the enrolled chancery copy. online copy
Godwin, G.E., nd, Licence to Crenellate Allington Castle, Kent, 1281 ref. PRO E329/470 online copy
Lyte, H.C. Maxwell (ed), 1901, Calendar of Patent Rolls (1272-81) p. 437 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. 194
King, D.J.C., 1983, Castellarium Anglicanum (London: Kraus) Vol. 1 p. 240n2
Brown, R.A., 1954, English Medievlal Castles p. 203 fig97
Turner, T.H. and Parker, J.H., 1859, Some account of Domestic Architecture in England (Oxford) Vol. 3 part 2 p. 403 online copy

Pencester , Sir Stephen of (d. 1298)

Pencester (Penchester, Penshurst), Sir Stephen of (d. 1298), administrator, is of obscure origins—surprisingly so, in the light of his prominence later. Pencester first appears in royal records in June 1263, when, probably already a knight, he was made captain to repress disorder in Sussex and Kent. He must already have acquired administrative experience, perhaps in the service of the Clare lords of Tonbridge, 5 miles from Penshurst. If so, he changed his allegiance, once civil war began to divide local society, to the Lord Edward, who was henceforth his patron. He was certainly unsuccessful as captain: his powers were given to Roger of Leybourne in December 1263. Once royal authority was restored in 1265, however, Pencester's career revived. Keeper of Hastings, Winchelsea, and Rye from November 1265, he became constable of Dover Castle, initially as Edward's deputy, in December 1267, and sheriff of Kent from 1268 to 1271. In August 1271 he was first referred to as warden of the Cinque Ports; Leybourne's death in that year probably offers a partial explanation for his rise to local prominence. Thereafter Pencester served as both warden and constable until his own death. (Eales)
Margaret, a member of the de Burgh family, though her exact parentage is unclear. (Eales)

Biographical source include;

Richard Eales, 2004, ‘Pencester , Sir Stephen of (d. 1298)’ Oxford Dictionary of National Biography (Oxford University Press) online copy (subscription may be needed)