The sitter was the fourth son of Sir Thomas Trollop of Casewick Hall, near Stamford, Lincolnshire. The family had strong connections with Pembroke College, Cambridge, and William was a Fellow of the College from 1731 until his death in 1749. This portrait is one of five portraits that were commissioned by John Arden, of Harden Hall, Tarporley, Cheshire, between c. 1746 and c. 1755. The sitters were Arden himself; the Rev. Sir William Bunbury of Mildenhall, Suffolk; William Chaworth, of Annesley, Nottinghamshire; Wrightson Mundy, of Markeaton, Derbyshire; and William Trollop (D'Oench, op. cit., 'List of Works', nos. 4, 20, 29, 116 and 157). All five were sold at Sotheby's, London, on 10 March 1965, lots 108-111a. Another version of Trollop's portrait, with a different over mantle painting, was by descent in the Trollop family until it was sold at Sotheby's, London, 13 July 1994, lot 50.