Before the appearance of this series (1914-65), the pre-thirteenth-century documents of Yorkshire were largely unpublished. This thirteen-volume collection was well respected for its extensive nature and the high quality of its editing. Volume 11 (1963) contains texts relating to the Percy fee and William de Percy II in 1166.

This thirteen-volume series, which first appeared between 1914 and 1965, is an extensive collection of the pre-thirteenth-century charters and related records of Yorkshire, which had previously remained largely unpublished. The first three volumes were edited by William Farrer (1861-1924), after whose death Charles Travis Clay (1885-1978) took up the task. The series was well respected for the quality of Farrer's editing, which was surpassed only by that of Clay in the later volumes. Volume 11 (1963) is devoted to the Percy fee and aims to be a survey of the land which constituted the knights' fees held by William de Percy II in 1166. The Latin texts presented here are accompanied by English notes and discussion of points of interest. The volume also contains facsimile plates of select documents as well as detailed indexes.