Collection comprises correspondence with Philip Hammersley Leathes, manuscript papers, diaries, devotionals, dictionaries and pedigree rolls, title deeds and indentures, printed books and pamphlets, catalogues and the manuscripts of the architect, John Carter, [1350-1863]. Notably including correspondence from George Nayler of the College of Arms and Nicholas Carlisle, Secretary of the Society of Antiquaries, relating to publications of the Society, discoveries of antique brass plate, and the exchange of manuscripts between antiquaries, [1790-1838]; loose manuscript papers collected by Leathes, describing ornamentation in early printed devotionals, a fictional narrative entitled 'The amorous Jill: A tale', narrative of the Lisbon earthquake of 1755, notes relating to the observation of comets, including the comet of 1811, copies of charters of the reigns of Edward IV and Henry VII, papers relating to the Portland Vase, British Museum, fragments describing inscription on newly discovered brass plate, 1747-1829; pedigree rolls tracing the lineage of the English Crown, [1450, 1762]; manuscript volumes including collection of biblical extracts, liturgical handbook, autograph book with colour illustrations, antiquarian ephemera such as funeral memorials, armorials and the creation of nobles, volume by Francis Harrison entitled, 'The elements of navigation' with colour charts, tables and illustrations, dictionaries of Celtic and Saxon words, notes on the teaching of mathematics, commonplace book drawing on ancient and modern authors, manuscript diary including progress of architectural tour of Europe; title deeds and indentures for families in Nottingham, Southampton, London and Hungerford, residency certificates in Buckinghamshire and Northamptonshire, 1650-1751; printed books and pamphlets on the subjects of antiquarianism, genealogy and architecture, 1778-1853; manuscripts of John Carter, architect, acquired at his death in 1817 by his executor, Leathes, notably including autobiographical notebooks by Carter describing architectural subjects and tours, commonplace book, correspondence with Leathes, loose notes on linguistics and the ships of the Russia Company, obituaries of Carter and sale catalogue from his estate, 1700-1818; manuscript catalogues and display captions relating to the Leathes' papers, King's College London, 1819, 1837.

Copy notes and diagrams, 1988, on 'General theory of colour', and planetary motion, with diagrams and covering letters; paper, Jul 1988, on 'The foundations of knowledge', listing an ideal syllabus.