The collection of over 700 documents was deposited in the Library by F. H. Mainprice of Taylor Kirkman and Mainprice, solicitors to the Hospital and Library, in January 1942. The documents deal mainly with land in Salford, Broughton, Kersal and Manchester and date from the C15th-C19th. The order in which the Library received the documents has not been altered although deeds in some bundles have been placed in chronological order. The deeds are now found in 20 boxes. Descriptions of the collection were made by Hilda Lofthouse (Mun.E.7.7-E.7.12) and by Ian MacAlpine (E.8.3-14) (1990-91).
James Chetham of Smedley (bapt 1682 d 1752) inherited on his father George's death in 1729 lands in Broughton, Salford, Moston, Failsworth, Chetham, Pendlebury and Rochdale. In 1752 the estates transferred to his sister Ann Chetham. On her death in 1762 the whole of her real estate was left to her cousin Edward Chetham of Nuthurst (1689-1769). He had inherited by will the bulk of the estates of the Chethams of Castleton in 1749. Thus he united for the first and last time the properties of all the branches of his family. Following his death the Chetham estates were divided and the land in Broughton and Salford etc became the property of Mary, younger sister of Edward, and wife of Samuel Clowes the younger. She died in 1775 having survived her husband by about two years and by her will left her estates to her eldest son Samuel. The estates then descended through the Clowes family.
The Clowes deeds were deposited in the John Rylands Library in June 1933 by Legh Algernon Clowes. They appear to have been well used by local historians including H. T. Crofton, C. W. Sutton and Ernest Axon, and by the contributors to the Victoria County History of Lancashire. A good many documents referred to in these publications as Clowes deeds are no longer in the collection at Rylands, and it appears that the Mainprice deposit (1942) is that part of the Clowes collection that relates to Salford, Broughton etc. If so, then some documents are missing. Crofton refers to a map of 1755 of the Clowes estates, for example which is neither in the Clowes collection nor the Mainprice deposit.