Luke Gardiner, 1st Viscount Mountjoy (1745-1798), was the scion of a family that became extremely wealthy as a result of clever land acquisitions and urban development on the north side of Dublin. Educated at Eton and Cambridge, he went on the Grand Tour with his brother William, travelling to France and Italy (1770-1). Gardiner was elected to the Society of Dilettanti in 1773 and sat to Sir Joshua Reynolds for this portrait in February and March that year. In the same year he married Elizabeth Montgomery, daughter of Sir William Montgomery, 1st Bt., and commissioned from Reynolds the celebrated portrait of his wife and her two sisters, The Montgomery Sisters, one of Reynolds' largest and most elaborate attempts at what the artist referred to as the 'grand style' which was to remain in the possession of Mountjoy until it was bequeathed to the London National Gallery in 1837 (London, Tate Britain). Alongside his interest in the arts, Gardiner pursued a political career as Member of Parliament for Co. Dublin (to which he was elected in 1773). A moderate on constitutional issues and a firm believer in public order, he was also a man of strong principles and in 1778 introduced legislation aimed at alleviating many of the economic difficulties faced by Catholics; he also promoted the interest of Dublin and its surrounding areas. Like his father and grandfather he also developed the Gardiner estate and in the 1770s was responsible for the development of Temple, Eccles and North Great George's Streets, and later in the 1790s for Mountjoy Square and Rutland Square. In 1782 he was raised to the peerage as Baron Mountjoy, and six years later was created Viscount Mountjoy, reflecting the family's influence and years of political service. With his first wife, who was to die in childbirth, he had his only surviving son Charles, later Earl of Blessington (1782-1849; see Christie's, London, 8 December 2010, lot 273), and he later married Margaret Wallis.
Reynolds painted another version of this portrait; in a letter, believed to date from July 1773, he told Luke Gardiner ' I shall send away your picture (the best of the two) immediately; the other I know is to remain here. I have forgot what place it is to be sent.'