John Sheffield succeeded his father as third Earl of Mulgrave in 1658, and was known as Mulgrave until created marquess of Normanby in 1694 and finally Duke of Buckingham and Normanby in 1703. He went to sea at the age of 18 and served in the second and third Anglo-Dutch Wars. After the Battle of Solebay, where he served gallantly as a volunteer, Mulgrave was appointed captain of the ‘Royal Katherine’ (see BHC3606). In 1680 he commanded a relief expedition to the English garrison at Tangier, but did not serve afterwards. He devoted himself to the court, politics and writing, holding high office under James II, William III and Anne. He was a friend of both John Dryden and Alexander Pope. He built Buckingham House (later Palace), on the western edge of St James Park, between 1703 and 1705.

He is shown wearing Greenwich armour and a brown full-bottomed wig and the riband and Lesser George of the Order of the Garter. He is holding in his left hand a wand, and on his left is the large gold key with the cipher ‘J.R.' of his office as Lord Chamberlain. The portrait is signed ‘G Kneller’, and has an inscription, probably later, ‘John Earl of Mulgrave, Lord Chamberlain 1688’.