Shackleton replaced William Kent as Principal Painter in Ordinary to George II in 1749 in which post he remained until his death in 1767, when he was replaced by the artist who painted the official portraits of George III, Allan Ramsay. There are many autograph full-length versions of Shackleton’s official portrait of George II (Wentworth Woodhouse, Scottish National Portrait Gallery, British Museum and Fishmonger’s Hall), none surprisingly in the Royal Collection. This is a three-quarter-length reduction said to have been acquired by William IV from the Pownall Estate; if this is so it must be the painting for which Shackleton was paid £55 15s 6d in 6 July 1757 by Thomas Pownall, Governor of Massachusetts Bay. At this price the painting would probably have been either entirely or largely autograph; the high quality bears this out. The sitter is shown wearing robes of state with the collar of the Order of the Garter, resting his left hand on his hip and holding a sceptre in his right hand.