The sitter was the only son of Charles William Stewart, 3rd Marquess of Londonderry (1778-1854), and his first wife Catherine, youngest daughter of the 3rd Earl of Darnley. His father, the half-brother of Viscount Castlereagh, the Foreign Secretary, whom he succeeded as 3rd Marquess of Londonderry in 1822, was a distinguished soldier and diplomat, who served under the Duke of Wellington in the Peninsular War and was later Ambassador to the Court of Vienna at Vienna. Frederick William Stewart, later 4th Marquess of Londonderry (1805-1872), is shown in this portrait at the age of thirteen. He was only seven years old when he lost his mother while his father was serving in the army overseas, and he was then looked after by his uncle and aunt, Lord and Lady Castlereagh, before being sent to Eton in 1814, where he was educated until 1820. In later life he was Member of Parliament for County Down (1826-52), a Lord of the Admiralty (1828-30), Vice-Chamberlain of the Royal Household (1834-35), a Privy Councillor, and served as Lord Lieutenant of Down (1845-60). He married Elizabeth (d. 1884), daughter of Robert, 3rd Earl of Roden, widow of Richard Wingfield, 6th Viscount Powerscourt, in 1846, at the British Embassy in Paris, but remained childless and was succeeded by his half-brother George Stewart. This portrait passed by inheritance through his wife to her eldest son from her first marriage.
The sitter's uncle, Viscount Castlereagh, who only succeeded as the 2nd Marquess of Londonderry at the very end of his life in 1821, and his father, the 3rd Marquess of Londonderry, were among Lawrence's most important patrons. His father, who entered Lawrence's life comparatively late, around 1811, when Lawrence had already established himself as the pre-eminent portrait painter in England, formed a close friendship with the artist, of whom he was very supportive. Crucially for the development of Lawrence's career it was the 3rd Marquess who asked the Prince Regent, later King George IV, who had never patronised Lawrence, to sit for the celebrated full-length which the artist exhibited in 1815 (Garlick, op. cit., no. 325 (c)), the success of which helped secure Lawrence the commission for the heroic series of portraits for the Waterloo Chamber. When Ambassador to the Court of Vienna, to which he was appointed in 1814 at the time of the Vienna Congress, the 3rd Marquess also took an active part in arranging Lawrence's triumphant continental progress to take likenesses for the Waterloo portraits which helped spread the artist's fame through Europe: Tsar Alexander sat to Lawrence in his presence when at Aix-La Chapelle for the Congress of 1818 and Lawrence stayed with his friend when he visited Vienna the following winter. The 3rd Marquess was also instrumental, when Ambassador to France, in tempting Lawrence to visit Paris to see Napoleon's looted treasures before they were packed and returned to Italy.
In all, over the course of nearly forty years Lawrence painted a celebrated series of portraits of the Londonderry family, among which are some of his most best known works. Together this outstanding series of portraits represents the most important strand of patronage from one family that the artist received in his career. The Londonderry family's patronage began in the early stages of the artist's career, when he was in his late twenties, and continued until the end of his career. Viscount Castlereagh first sat to Lawrence in 1794, and the resultant three-quarter-length was exhibited at the Royal Academy that year (Garlick, op. cit., 1989, no. 507 (a)). He was to sit to him again in 1810 for a half-length (London, National Gallery; see fig. 1); in 1814 for a three-quarter-length portrait, exhibited at the Royal Academy that year; and finally in 1821 for a full-length, in peer's robes with the Garter and the Garter Collar as he wore at the coronation of King George IV (Garlick, op. cit, pp. 227-8, nos. 507 (b),(c), and (d)). Alongside these portraits, Lawrence also executed a three-quarter-length portrait of Castlereagh's wife Amelia (1772-1829) in the year of their marriage in 1794 (Garlick, op. cit., p. 228, no. 508 (a)).
Lawrence's earliest portrait of Charles, 3rd Marquess of Londonderry, was first mentioned in June 1810 and was exhibited at the Royal Academy in 1811; it is now untraced and is thought to have been destroyed in a fire at Wynyard House in 1844 (Garlick, op. cit., no. 509 (a); see fig. 2). He sat again to Lawrence in c. 1811 for a celebrated portrait which exists in two autograph versions, in which the 3rd Marquess is shown in scarlet and gold hussar uniform with the Peninsular medal that he had been awarded after the Battle of Talavera in 1809, which is one of the most heroic of any of the artist's portraits (Garlick, op. cit., under no. 509 (b)). A final portrait of the 3rd Marquess, of half-length format, which remained unfinished at the artist's death, was undertaken in Vienna in 1818 (Garlick, op. cit, no. 509 (c)). Complementing these, the 3rd Marquess also commissioned a half-length portrait of his second wife, Frances Anne, the only daughter of Sir Henry Vane Tempest, a considerable heiress whom he married in 1819, and a full-length portrait of his second wife together with their son George, later 5th Marquess, in 1828, of whom Lawrence also executed a portrait as a young child in 1824 (Garlick, nos. 510 (a) and (b) and 512).
This portrait of the 3rd Marquess's only son from his first marriage was executed in 1818 and is said to have been painted at Lawrence's request rather than as a result of a commission. A version of the portrait which Garlick considered 'less lively' than the present picture on the basis of photographs is in a British private collection (Garlick, op. cit., 1989). The present portrait passed by inheritance through the sitter's wife into the collection of the Viscounts Powerscourt, at Powerscourt, Co. Wicklow, Ireland, by whom it was sold at Christie's in 1903. It was subsequently owned by the prominent London art dealer Asher B. Wertheimer, who having emigrated to Britain in 1830 became one of the most successful art dealers of his generation and is immortalised, with his family, in a series of outstanding portraits by John Singer Sargent, which he bequeathed to the National Gallery. The portrait later entered the distinguished collection of another German emigrant, the prominent New York businessman, Louis Stern.