Rectangular miniature in watercolour on ivory, unframed but in a larger rectangular beige card mount, with a gilded edge to the window. It is one of a pair with MNT0074, which depicts Mrs Cox. The sitter is shown against a brownish background, bust length, turned very slightly to his right but facing forward, wearing full-dress lieutenant's uniform, with epaulettes. He has refined features, including grey eyes and a high forehead, with light brown and slightly greying hair parted on his left, and redder side-whiskers to below his ears. An inscription by the artist on the back reads: 'Feby. 1847. / Lieut. Cox, R.N. / painted by William Egley, / 75 Connaught Terrace, / Hyde Park.'

Cox, a naval surveyor, was born on 4 July 1809. He entered the Navy as a 1st-class volunteeer in 1824 and passed his lieutenant's examination in 1830, though not commissioned until March 1840. Even before becoming a 'passed midshipman' he had early experience of surveying in small vessels. This included in the 'Aetna' under Edward Belcher in north-west Africa (1831-32) and the 'Fairy' in the Channel. He was also involved in slave-trade suppression between Cape Verde and the Equator in the 'Britomart', 1833-36. He was then in the 'Harlequin' in the Mediterranean under two aristocratic captains, the Plymouth guardship 'Impregnable' under Sir Graham Moore and the 'Stag', Commodore T. B. Sullivan, in which he went to South America and had his first temporary command in a ketch in 1841-2. In December 1842, under Alexander Vidal in the 'Styx', he helped survey the Azores and Madeira, and from April 1845 began a period in the Channel in the 'Dasher', steam packet, initially as Assistant Surveyor under Capt. William Sheringham. He succeeded him in command in 1853, and was himself promoted to Commander on 1 January 1857. During the later part of this period he re-surveyed Plymouth Harbour and Sound, his chart being sent to the 'Paris Exhibition' (probably the Exposition Universelle of 1855) as an example of Admiralty work. From August 1860 he was attached as an extra commander to successive flagships on the Australian Station, but detached on surveying the coast of Victoria until his retirement in October 1866. His promotion as a captain on the retired list was backdated to 4 September and in April 1870 he was awarded a naval pension of £65 p.a. He died on 10 May 1872 at his home, 62 Forest Hill Road, London.

The painter, Egley (1798-1870), born in Doncaster, was largely self-taught. He nonetheless became a dedicated and highly successful London miniaturist, especially of aristocratic subjects, and noted for the truth to life of his representaton and his fine colouring. From 1824 to 1869 he was a prolific exhibitor at the Royal Academy (though not in all years) and elsewhere, and it is a characteristic of his work that he usually fully signed and dated it, with an address, on the back. This example and its pair, with his recorded exhibiting address for 1848 at the Society of British Artists, shows he was fairly briefly living at 75 Connaught Terrace at this time, as was his painter son, William Maw Egley. These miniatures of Cox and his wife were originally a fine pair: this one remains so, in good condition, but the other is damaged. It is possible they were a marriage pair, painted shortly after that event which occurred in Kennington, London, on 17 April 1845. They were bequeathed to the Museum by a descendant, Isobel Roe, in 1968 with those of the Bloyes (MNT0068, MNT0069, Cox's aunt and naval uncle) and another family portrait (PAG6466).