The sitter was the eldest son of Sir Edward Turner, of Hallingbury Place, Essex, Speaker of the House of Commons, Lord Chief Baron and Lord Chancellor (1616-1676), and his first wife, Sarah (1624-1651), daughter and heir of Gerard Gore, merchant and alderman of London. He was admitted to the Middle Temple in October 1661 and made a Fellow Commoner at Christ's College, Cambridge the following February. Turner was a courtier to Charles II, being knighted in February 1664 and then appointed a Gentleman of the Bedchamber. He was called to the bar in 1672 and was later a Member of Parliament for Orford, almost continuously from 1701 until his death.
In May 1667, Turner married Lady Isabella (d. 1690), daughter of William Keith, 7th Earl Marischal. The couple had two sons and five daughters, and lived at Hallingbury Place, Great Hallingbury, Essex, which had been purchased by Turner's father in 1660. King Charles II was godfather and the Duchess of Monmouth godmother to Turner's eldest son, who was named in the King's honour. Great Hallingbury had to be sold on Turner's death to cover outstanding debts: it was purchased in 1729 by Jacob Houblon (and later demolished in 1922). Turner's great-grandson, Edward Turnour Garth Turnour, later 1st Earl of Winterton in the Irish peerage, inherited the remaining family estates, including Shillinglee Park, in 1744.
John Michael Wright was apprenticed to George Jamesone in Edinburgh before travelling to Rome in the 1640s. By the 1660s, he was running a successful practice in London and competing with Sir Peter Lely as the most fashionable portraitist of the Restoration Court. The sitter's decision to commission a portrait from the artist may have been prompted by the fact that Wright had painted his father, Sir Edward Turner, as part of a larger project initiated by the Aldermen of the City of London in 1670 to honour the judges responsible for solving the multitude of issues resulting from the Fire of London.
Edward Harley, 2nd Earl of Oxford and Mortimer, who acquired this portrait after the sitter's death, was educated at Westminster School and Christ Church, Oxford, and acted as Member of Parliament for Radnor and Cambridgeshire, before succeeding his father as 2nd Earl in May 1724. On marrying the heiress Henrietta Cavendish (1694-1755), only daughter of John Holles, 1st Duke of Newcastle upon Tyne, he inherited Wimpole Hall, Cambridgeshire, and later, in 1716, inherited Welbeck Abbey, Nottinghamshire from his mother-in-law, Duchess of Newcastle. He founded a very substantial collection of pictures as well as a celebrated library.
The signature recorded on the reverse of the canvas corresponds with that inscribed by Vertue.