A three-quarter-length portrait to left in a sleeveless leather jerkin over a buff coat, heavily barred with gold down the length of the sleeves. He wears the ribbon of the Garter, a pink sash around his waist, and a collar and cuffs made of Flemish bobbin lace. He holds a baton in his right hand, his right arm rests on an anchor fluke and his left hand is on his sword belt. The background is of rock on the right and a dramatic sky beyond on the left.

After fighting for Charles I in the Civil War and being captured, in 1650 Monck went with Cromwell in his Scottish campaign, by which time he was an eminent soldier in the Parliamentary service. In 1652 he was one of the three officers appointed as Generals-at-Sea, though he had no previous sea experience. He fought the Dutch at the Battle of Portland the following year, and at the Gabbard he was in sole command for most of the action once Richard Deane had been killed. At Scheveningen, during the last battle of 1653, he again had sole command owing to the illness of Blake. There he inflicted the final defeat on the Dutch, which included the death of Maarten Tromp. In 1660 he was chiefly responsible for the restoration of Charles II. In the Second Dutch War, 1665-67, he was at first deputy Lord High Admiral while the Duke of York was at sea with the fleet, and in 1666 was given joint command with Prince Rupert. During the Four Days' Fight, 1-4 June 1666, he fought the Dutch commander, de Ruyter, alone with only part of the fleet for the first three days but in the St James's Day Fight on 25 and 26 July combined with Prince Rupert to defeat him. Albemarle was in charge of the defence of the Medway and Chatham when the Dutch admiral took his revenge in the celebrated Dutch raid the following year. The painting is inscribed 'Duke of Albemarle' in the bottom left. It is one of the 'flagmen' series commissioned by Charles II's brother James, Duke of York after the Battle of Lowestoft, 3 June 1665. This was the first major action of the Second Dutch War, in which James commanded the fleet. It was among those listed by Pepys as begun or finished when he visited Lely's studio on 18 April 1666.

Lely, a Dutchman who arrived in England in 1641 after the death of Van Dyck, soon became his successor as leading portraitist of the day. He worked for Charles I, continued to flourish under the Commonwealth and Protectorate, and after the Restoration of 1660 was appointed Principal Painter to Charles II. The full 'flagmen' set consists of thirteen individual portraits, of which George IV presented eleven plus a copy of that of Admiral Sir John Lawson (BHC2833) to Greenwich Hospital in 1824. The originals of Lawson and of Prince Rupert were retained in the Royal Collection, although William IV presented an extended full-length copy of the latter (BHC2990) to the Hospital in 1835.