Records of the Duchy of Lancaster

The origins of the Duchy of Lancaster lay in the desire of Henry III (1216-1272) to establish his youngest son, Edmund Crouchback, as a territorial magnate in England, following his failure to secure for him the Sicilian throne in 1258. Thus, in the aftermath of the Barons' War, Edmund was endowed with the extensive estates of the defeated leader of the baronial rebellion, Simon de Montfort, Earl of Leicester (d1265). Then in 1267 he was created Earl of Lancaster and granted all the royal demesnes in the county of Lancashire.

Edmund was succeeded by his son, Thomas of Lancaster, who increased the inheritance by marriage, and from whom the estate passed to Thomas's brother Henry, third Earl of Lancaster, in 1322. Henry's son, also called Henry (of Grosmont), was created the first Duke of Lancaster in 1351. Henry was succeeded, in 1361, by his daughter Blanche and her husband, John of Gaunt. They in turn were succeeded by their son, Henry Bolingbroke, whose accession as King Henry IV in 1399 brought the Lancaster inheritance into the possession of the crown.

However, Henry did not allow the inheritance to be merged into the crown's other lands, and it retained its separate identity as the Duchy of Lancaster. It continued, and continues today, to be administered separately from the other crown estates.

On the accession of Henry IV in 1399, the term Duchy came to refer to the whole of the Lancaster estate rather than just the County Palatine as had been the case before. The county of Lancashire was raised to palatine status in 1351, which gave to the duke sovereign rights in the county in the spheres of justice and administration.