Born John Lockhart, this Scottish officer was fifth son of Sir James Lockhart, 2nd Baronet of Carstairs, and served as a lieutenant in Peter Warren's flagship at the First Battle of Finisterre in 1747. In 1756-58 he commanded the 'Tartar' (28 guns) with great success in the Channel, sweeping up French prizes of equal or superior force, and receiving the freedom of Plymouth and an award of plate from the London merchants for his efforts. The Admiralty also commended him and appointed him to the newly built 'Chatham' (50). In her, in 1759, he was involved in the preliminaries of Hawke's Quiberon campaign in Robert Duff's scouting squadron and, though only a witness rather than in participant at the Battle of Quiberon Bay that November, he became Hawke's flag-captain in the 100-gun 'Royal George' immediately afterwards, when John Campbell (who had commanded her there) was sent home with the victory dispatches. In 1760 Lockhart adopted the name of Ross as a condition of inheriting his brother's Scottish estate of Balnagowan, Ross-shire, and went onto half-pay from late 1761 prior to marrying in 1762. He thereafter managed the estate until returning to sea in 1777 in command of the 'Shrewsbury', 74 guns, in the Channel Fleet. He fought at the controversial Battle of Ushant in July 1778, inherited the family baronetcy from his last surviving elder brother that August, and became a rear-admiral in 1779, loyally remaining in the Channel Fleet during a very difficult period for the Navy. He was involved in all three reliefs of Gibraltar; first by Rodney in 1779, under whom he also fought in the 'Moonlight Action' against the Spanish off Cape St Vincent, in January 1780; then that led by Darby in 1781 and finally Howe's relief of 1782, after which he came ashore. His final promotion was to Vice-Admiral of the Blue in 1787. Ross had become 6th baronet because none of his four elder brothers had male heirs. On his own death, at Balnagowan in June 1790, he was succeeded by his son Charles.

This oil portrait is a small full-length of non-standard size (though within that of a standard 50 x 40-inch half-length canvas). It shows Ross in a rugged clifftop coastal setting, with a classical rostral column to the left in front of a vigorously sinuous tree rising behind, and a ship at sea to the right below. He is turned a little to viewer's left, looking upward, wearing the 1767-74 captain's undress uniform (over three years seniority) and is standing in a relaxed pose with his right hand and right foot on the base of the column. His right hand is kid-gloved, holding its left pair on the column plinth. Zoffany had arrived in London in 1760 and in 1763 found favour among an elevated Scottish clientele surrounding Lord Bute, then the Prime Minister, which may explain this portrait's origins. The uniform gives its earliest date and Zoffany's departure for Italy in 1772 the latest, though it is probably relatively early in that span. The setting is clearly tailored to the sitter: the naval column and ship speak of Ross's undoubted professional prowess and the landscape, presumably intended as Scottish, supports the traveller and naturalist Thomas Pennant's report (as cited in DNB) that as a landowner he was principally devoted 'to the improvement of his estates and the condition of the peasantry'. According to Pennant he became known as 'the best farmer and the greatest planter in the country; his wheat and turnips showed the one, his plantation of a million pines the other'. Note that the image purporting to be of this oil in the NMM 'Concise Catalogue of Oil Portraits' (1986) is mistakenly from John McCardell's print of the c. 1762 portrait of Ross by Reynolds. Here the lean and dashing figure shown by Reynolds has filled out into a more prosperously overweight but still commanding middle age.