Prior to 1485 this series consists mainly of grants, charters, letters of inspeximus and other documents under the great seal to the dukes of Lancaster and their predecessors in title, granting land, offices and privileges.
The charters include evidences of all the major families whose estates became at some time absorbed into those of the Duchy: for example, Ferrers, Lacy, Warenne, Chaworth and Bohun.
Also represented are the archives of religious houses whose estates were acquired by the Duchy at the time of their dissolution: the abbey of Furness and the priories of Cartmel, Conishead and Burscough.
The series includes two letters of protection issued under the great seal; safe conducts; pardons; formal receipts; summonses to parliament or to the council; letters and commissions concerning military service; writs to royal officers prohibiting intervention in Duchy liberties; and judicial writs.
After 1485 the series consists mainly of letters patent and other formal documents under the Palatinate and Duchy seals: that is, records created by the Duchy administration, rather than evidences pertinent to the endowment of the dukes. These include grants of land and office, and commissions of survey or enquiry.
The series includes some strays, including an illuminated charter of 1462, in favour of the town of Nottingham, still in its tooled leather box.
This series contains records which pre-date the creation of the Duchy of Lancaster.