(Updated, January 2016) A three-quarter-length portrait to left wearing flag officer's undress uniform, 1767–83. His outstretched right hand rests on his sword and his left hand is positioned in his breeches pocket. He stands against a coastal background to denote his naval career. The portrait shows the sitter's hair powdered. (He actually wore his own hair rather than a wig throughout his life.)

Keppel was the second son of the second Earl of Albemarle and one of a powerful Whig family of Dutch origin who came to England with William III. In 1740 he sailed under Commodore Anson in the 'Centurion' on his four-year voyage round the world. In 1749, as a commodore, he himself commanded the 'Centurion' to the Mediterranean, taking Joshua Reynolds with him, which marked the beginning of a close lifelong friendship between them. Reynolds was en route for Italy, where he stayed for two years to travel and study. In 1758 Keppel commanded a small expedition, which captured the island fortress of Goree, off Dakar on the West African coast. At the Battle of Quiberon Bay, 20 November 1759, he commanded the 'Torbay', 74 guns, and played a notable part by sinking the French 'Thesée', 74 guns. In 1761 he commanded the naval forces at the capture of Belle Ile and in the following year was second-in-command to Sir George Pocock at the capture of Havana. During this time he became a rear-admiral. On this expedition his elder brother, George, third Earl of Albemarle, was Commander-in-Chief and another soldier brother, William, was a general officer on his staff. Keppel commanded the Channel fleet in the early years of the American War of Independence, 1775–83, but found the fleet unprepared. On 27 July 1778 in the 'Victory', 100 guns, he led the fleet in an indecisive battle with the French off Ushant. His second-in-command, Sir Hugh Palliser, gave him inadequate support and the resulting quarrel split the Navy. Keppel, a Whig, was tried by court-martial, at which Palliser, a Tory, conducted the prosecution. When Keppel was acquitted he became the hero of the hour but the whole affair was politically charged. Keppel gave this portrait to John Lee, who acted without fee as his court-martial defence lawyer at Portsmouth in 1779 and later became Attorney General. He also ordered several identical versions of this painting to give to his other supporters and the presence of the sword may symbolically allude to its formal return following the court martial. Keppel subsequently retired from active service, entered Parliament as MP for Surrey, and became a Viscount in 1782. Personally he was a man of great charm and Admiral Boscawen judged there was ‘no better seaman than Keppel, few so good, and not a better officer’. Small in stature and popular with seamen, who called him 'Little Keppel', he lost may of his teeth to scurvy during his voyage with Anson and all but early portraits show the permanently dented nose he got when attacked by a footpad.

In 1740 Reynolds was apprenticed to the portrait painter Thomas Hudson (1701–90) and began portrait work in his native Devon. In 1753, on his return from Italy, he set up in London and rapidly began to make a name as portrait painter, profoundly influenced by his time in Italy. He became the first President of the Royal Academy in 1768 and was knighted in 1769. He was the most influential figure of the century in elevating British painting and portraiture. Reynolds borrowed poses from the old masters and by 1759 he had created social portraits in a new style that were deemed fresh and modern, and yet dignified the status of the sitter.