The Registrum Antiquissimum is the earliest complete cartulary of Lincoln Cathedral. It was written mainly in the third decade of the thirteenth century, and prepared from the original texts, many of which have not survived. Its editor, Canon Foster, noted that its writer "copied with literal accuracy. As a consequence his texts may be relied upon". The charters illustrate the history of an English secular cathedral church in respect of its organisation and personnel, its endowments and its franchises. The Introduction notes that the texts of 7,826 charters have survived of which 4,200 are the original documents. There are 1,073 charters in the Registrum Antiquissimum. The documents in the Registrum Antiquissimum include charters of the possessions not only of the common of the canons, and of the prebends, but also of the see of Lincoln. These possessions lay dispersed throughout the diocese of Lincoln which, as constituted by William the Conqueror, stretched, until the middle of the sixteenth century, from the Humber to the Thames.
It comprised the counties of Lincolnshire, Leicestershire, Northamptonshire, Rutland, Huntingdon, part of Hertfordshire, Bedfordshire, Buckinghamshire, and Oxfordshire. Outside the diocese, the charters relate to land in London and in the counties of Berkshire, Derbyshire, Hampshire, Kent, Nottinghamshire, Surry, and Yorkshire. But it is for the history of the Northern Danelaw that the Lincoln charters are of first-rate importance.