Palmer's papers consist of extensive transcripts, notes, and original items relating principally, though not exclusively, to the history of Cambridgeshire and its parishes. Among the primary materials are a journal of an Italian tour kept by Peter Cowling in 1786; a diary of M. F. Dayrell for 1866; the journal and sketch book maintained by Peter Cowling of Fenstanton on a round trip from Fenstanton to Oxford in 1810; a day book of John Davey of Hadstock, carter, dung and straw merchant, 1818-1834; and a prescription book of Thomas Frewen, the Sussex apothecary and physician, 1750-1755. Some correspondence and notes on seventeenth century Norfolk assize records, purchased by Palmer in 1934, were transferred to the Public Record Office in 1968. A typescript catalogue is available in the Manuscripts Reading Room.