In 1434 June 1, Henry, earl of Northumberland, and the burgesses of the town was granted, by Henry VI, (In year 12 of his reign) a Royal licence to crenellate Alnewyke (Alnwick Town Wall)

"De includendo murando et battellando villam de Alnewyke
Licence, by advice of the council, for Henry, earl of Northumberland, lord of the castle and town of Alnewyk, co. Northumberland, and for the burgesses of the town ,to enclose the whole town with a wall and to machicolate and otherwise fortify the said wall. A great part of the town has recently been burned by the Scots with impunity."

Granted at Westminster, by privy seal.

The licence adds "A great part of the town has recently been burned by the Scots with impunity."

Original source is

• Calendar of Patent Rolls (1429-36) p345

(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;

• Brooke, C.J., 2000, Safe Sanctuaries (Edinburgh; John Donald) p99
  Coulson, C., 1995, 'Battlements and the Bourgeoisie: Municipal Status and the Apparatus of Urban Defence' in Church, Stephen (ed), Medieval Knighthood Vol. 5 (Boydell) p156n150
  Bates, C.J., 1891, Border Holds of Northumberland (London and Newcastle: Andrew Reid) p21
  Hodgson Hinde, J., 1858, A History of Northumberland (Newcastle-upon-Tyne: Society of Antiquaries of Newcastle-upon-Tyne)

More details about licences to crenellate can be found here.

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