The papers of Admiral John Markham include a mixture of official and personal correspondence. There are orders and certificates from the early part of Markham's career, including those while captain of HM ships SPHYNX and CENTAUR. There are also financial records (relating to uniforms, prize money and pay), correspondence relating to the Nore mutiny, as well as legal opinions, prize money and papers relating to Markham's own court martial in 1782.

The collection also includes a substantial amount of correspondence from various flag officers, including Admirals Murray, Vashon, Keith and Stanhope among others, and 150 letters from St Vincent while the latter was First Lord and Markham also sat on the Admiralty Board. Also included is correspondence from various naval captains and lieutenants, all arranged alphabetically, together with correspondence from other public and non-naval figures and a quantity of Admiralty correspondence covering such subjects as appointments, ship dispositions and material relating to the various naval enquiries including ship timber and construction, manning, pay, pensions and naval stores.

The papers also include family and personal correspondence. There are letters from Markham's father William (Archbishop of York), his mother Sarah, his wife Maria and other members of the Markham family. There are also letters from friends including Lord Mark Kerr and the Earl of Mansfield together with estate papers and various maps, charts and sketches.

Administrative / biographical background
John Markham (1761-1827) was the second son of William Markham, Archbishop of York. Markham entered the Navy in March 1775 serving on the ROMNEY under George Elphinstone. In March 1776 he transferred to the PERSEUS, also under the command of Elphinstone (see KEI/L/128, a logbook for the two ships covering the years 1775-6). In 1797 Markham sat on a number of courts martial following the mutiny at the Nore. When St Vincent was appointed 1st Lord of the Admiralty he selected as his sea lords officers who had served under him – Troubridge (whose papers the Museum also holds on long-term loan - see TRO) and Markham. Markham was elected MP for Portsmouth in 1801 and from then until 1804 his “career was identified with St Vincent’s” (Laughton/Morriss, 2004). St Vincent set about his controversial reforms with Markham working to take a bill through parliament intended to establish a parliamentary commission to investigate the Navy’s civil branch.