The papers form a full collection for all periods of Parker's service. There are official and private logs, 1794 to 1811, 1827 to 1834 and 1841 to 1852; official letterbooks, 1799 to 1834, and order books, 1795 to 1834, 1841 to 1857, and loose papers relating to his commands. Parker's personal papers include official service documents, his letters home, and his correspondence which includes letters from Sir James Graham (1792-1861), 1831-1845, Admiral Sir Thomas Hardy (1769-1839), 1831 to 1834, Gilbert Elliot, 2nd Earl of Minto (q.v.) 184l to 1848, and Admiral Sir Edmund Lyons (1790-1858), 1845 to 1854. There is a log of a Spanish ship captured by Parker in 1794 and a register of lading of Nuestra Senora de la Esperanza, captured in 1804. The collection also contains letters written to Dr Andrew Baird (q.v.) by Earl St. Vincent (q.v.). The final section, loaned in 1974, consists of two series of letters. The first consists of those received by Earl St. Vincent, 1791 to 1821, and includes some from Lord Nelson (q.v.), 1796 to 1804, and the second, letters to Parker, including Nelson letters, 1803 to 1805.

Administrative / biographical background
Parker was a nephew of Sir John Jervis (later Earl St. Vincent (q.v.)). He entered the Navy in 1793 as a captain's servant in the ORION and, as a midshipman, was present at the battle of the Glorious First of June 1794. He was then transferred with Captain (later Admiral) J.T. Duckworth (q.v.) to the LEVIATHAN and he went out to the West Indies in 1795. From 1796 to 1798 he was acting lieutenant of the MAGICIENNE and from 1798 to 1799 of the QUEEN, being promoted to lieutenant in 1799. He was appointed to command the VOLAGE and then the STORK, in which ship he returned home in 1800 and served for a year in the North Sea. He was promoted to captain in 1801 and during the following year commanded L'OISEAU, the HELDIN and the ALARM in home waters. Between 1802 and 1812 Parker was Captain of the AMAZON. He served in the Mediterranean under Nelson and sailed with him to the West Indies in 1805. From 1806 to 1810 he was employed mainly on the coasts of Spain and Portugal and from 1811 to 1812 in the Channel. Parker was then on half-pay until 1827 when he was sent to the Mediterranean in the WARSPITE, being Senior Officer in the Aegean in 1828. On his return home he was appointed Captain of the Royal Yacht Prince Regent until his promotion to rear-admiral in 1830. He was second-in-command, Channel Squadron, in 1831 and commanded a squadron on the coast of Portugal during the Carlist War, 1831 to 1834. He was knighted in 1834 and was a Lord of the Admiralty between August and December of the same year. From 1835 he again had a seat at the Board of the Admiralty until 1841, when he was promoted to vice-admiral and appointed Commander-in-Chief, East Indies, where he brought the First Chinese War to a successful conclusion. In 1845 he was appointed Commander-in-Chief, Mediterranean, a post he held until 1852 and which, from 1846 to 1847, was combined with a command in the Channel during the Portuguese Civil War. In 1851 he was promoted to admiral. He was Commander-in-Chief at Devonport from 1853 to 1857 and was promoted to Admiral of the Fleet in 1863. See Admiral Sir Augustus Phillimore, 'The life of Admiral of the Fleet Sir William Parker' (3 vols, London, 1876-1880). In 1834, as part of the UK government's Slave Compensation Commission, Parker was awarded a share of the compensation amount of £3,529 8s 10d for the Canaan estate and the enslaved people on it, in Westmoreland Jamaica with the 2nd Viscount St Vincent and Francis Love Beckford senior, almost certainly as a trustee (https://www.ucl.ac.uk/lbs/person/view/46475).