When George III was asked by Lord Eglinton to sit for the most fashionable portrait painter of the day, Joshua Reynolds, he replied: ‘Mr Ramsay is my painter, my Lord.’ Reynolds tried to gain royal notice with two speculative ventures – a portrait of George III as Prince of Wales (OM 1011, 401034) and an oil sketch for a depiction of his marriage to Queen Charlotte (OM 1012, 404353) – both of which remained on his hands. Reynolds was knighted by George III, made first president of the Royal Academy and Principal Painter to the King upon Ramsay’s death in 1784, but never asked to paint anything. That the Royal Collection has a fine group of Reynolds is entirely thanks to George IV, who commissioned portraits at the end of the artist’s life and acquired many examples of his earlier work like this one.

In 1758 the Duke of Cumberland sat to Reynolds for a full-length portrait now at Chatsworth. The Royal Collection has two versions of this much-copied portrait (OM 1009-1010, 400565 and 404541). This one may be the a replica ordered by Princess Amelia (the sitter's brother) in 1764 for 60 guineas. the Duke is shown wearing Garter robes and clasping his sword in his left hand; the plumed hat of the Order rests on a table on the left.

The Carlton House inventory values this portrait at 500 guineas and records it as hanging in the West Anti Room (seen in RCIN 922174), while also saying that it is at Sir Thomas Lawrence's (whether this is so that Lawrence can restore it or learn from it is not clear). It hung in the Waterloo Chamber, where Lawrence's Charles X (OM 890, 405138) now hangs, which suggests that it was an important link between the Grand Style portraiture of Reynolds and Lawrence.