Robert Harley, 1st Earl of Oxford and Earl Mortimer, KG PC FRS (5 December 1661 – 21 May 1724) was an English and later British statesman of the late Stuart and early Georgian periods. He began his career as a Whig, before defecting to a new Tory ministry. He was raised to the peerage of Great Britain as an earl in 1711. Between 1711 and 1714 he served as Lord High Treasurer, effectively Queen Anne's chief minister. He has been called a prime minister, although it is generally accepted that the de facto first minister to be a prime minister was Robert Walpole in 1721.