"Licence, because the town of Herewiche, co. Essex, is situated on the sea-coast and in front of the king's enemies and is without a castle or fortress for its safe-custody, for the king's kinsman Thomas Moubray, earl Marshal, to grant in mortmain a parcel of land within the town, containing 160 feet in length and 160 feet in breadth, not held of the king, to the burgesses of the town and for these to build on it a castle or fortress of stone and lime and to crenellate the same. "
Granted at Westminster, by King and for 20s. paid in the hanaper.
Original source is
(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.)
More details about licences to crenellate can be found here.
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