"letters directed to his knights and free men requesting them to make him an aid for the strengthen his castle at Leverpul."
Granted at Reading,
Although this document has been considered by some as a licence to crenellate the current opinion rejects this as a licence to crenellate.
Does not seem like a licence to crenellate to me, although clearly Royal consent to strengthen an existing castle.
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.)
The family was descended from Henry de Ferrers who arrived in England from Normandy during the reign of William I, and whose heir, Robert (d. 1139), was created earl of Derby by King Stephen. William Ferrers, fifth earl of Derby (d. 1254), married Margaret (d. 1281), eldest daughter and coheir of Roger de Quincy, earl of Winchester (d. 1264). Had some royal connection and favour, did sit in parliament in 1230, but not active in government.
Biographical source include;
More details about licences to crenellate can be found here.
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