The Tonson family papers consist of 8 boxes and 7 volumes, including:
- Boxes 1 to 8 (formerly MS 129) - Legal documents, including deeds, leases and wills, and accounts, financial records and correspondence relating to property owned by the Tonson family. Box 1 contains material concerning the Kit Cat Club portraits (NPG 3193-3235), this includes bills and receipts for picture frames and cleaning of portraits, list of subscribers to the Kat Cat Club 15 May 1702, toasts for the years 1712 and 1714, account of the Kit Cat Club, documents relating to the portrait of John Duke of Marlborough, plan of the hang of Kit Cat pictures in Barn Elms and bill for food and drink for the Kit Cat Club.
- Copy of the will of Jacob Tonson the younger (formerly MS 130) - Copy assumed to have been made after Jacob Tonson the younger's death in 1735, includes 5 loose pages which appear to relate to the estate of Richard Tonson and date from c. 1776.
- Account book (formerly MS 131) - Contains records of receipts and payments in connection with property, including servants' wages, building maintenance, rents and mortgages. 1767-1771
- Executor book (formerly MS 132) - Contains receipts, pasted to the leaves of the volume, relating to the settlement of legacies from the will of Jacob Tonson (1714-1767) by his brother and executor Richard Tonson (1717-1772), 1767-1772
- An account of securities and personalities found in the house of Richard Tonson Esq in his dwelling house at Water Oakley this 19th day of Oct 1772 (formerly MS 133) - Contains records of notes of hand, assignments of leases, mortgages, bonds, and cash found in the house, together with a loose leaf at the front of the volume inscribed 'Copy of Mr Mosely's will', c. 1772
- Heirs of Richard Tonson (formerly MS 134) - Account book maintained by William Baker relating to the estate of Richard Tonson, 1772-1774
- Account William Baker with heirs of Richard Tonson (formerly MS 135) - Includes a loose leaf summary of Tonson's accounts, 1772-1776
- Estate of Richard Tonson Esq deceased, October 9th 1772, William Baker, Administrator (formerly MS 136) - Includes copy of Richard Tonson's will and accounts relating to his estate compiled by William Baker, some loose pages are contained within the volume concerning monies received, 1772-1777