Mainly a collection of transcripts and original documents, treatises, notes and foreign and domestic pamphlets (some formerly in SP 16, SP 29 and SP 30) made by Sir Joseph Williamson, the Keeper of the State Papers from 1661 to 1702. The collection was made from the state papers in his custody, from other official historical records, and from private sources. They relate to heraldry, genealogy, diplomacy, the royal prerogative, the Coronation Claims Court, precedence, styles of foreign princes, etc., and include original letters patent and grants of arms, maps, plans, engravings and seals, English and foreign. The collection includes transcripts or notes by other record keepers such as Ambrose Randolph, Thomas Astle, John Brydall, and John Bruce.
To Williamson's collection has been added, from at least the early nineteenth century and probably earlier, a considerable number of miscellaneous items found in the State Paper Office, including more recently a series of domestic pamphlets.
The records cover a very wide variety of subjects: foreign (there is much material relating to Italy, Poland, Russia, Spain, France and the Netherlands), domestic, colonial, administrative, cultural, political, legal, heraldic, diplomatic and military. The content of the transcripts dates back to the thirteenth century.