The archive chiefly comprises the research papers, notes and transcriptions of Mary Bateson (1865-1906), historian and fellow of Newnham College, Cambridge, relating to her publications and lectures on medieval history from the mid-1890s until her death in 1906. There are extensive notes on Bateson's most significant editorial works, the Records of the Borough of Leicester (1899-1905) and Borough Customs (Selden Society, 1904 and 1906); and research for articles written for the English Historical Review. Other papers include notes on monarchs, primarily Edward I and Edward II, the Poor Law, Leges Burgorum (a form of law in Scottish towns created by David I), the Cinque Ports, other miscellaneous notes on English boroughs and towns, and several letters relating to her publications and research.
The archive also contains notes and transcriptions written by others, possibly assistants, students or other academics, primarily on medieval history. Many of Bateson's own notes are written on the backs of papers written by others. Several notes, including a set on examination entry forms, are dated some years after her death; although they too focus on medieval history, their relationship with Bateson's own papers is unclear.