William Augustus, Duke of Cumberland (1721-1765) was the third son of King George II and Queen Caroline. After a distinguished military career, fighting at the Battle of Dettingen and in the Netherlands he returned to England in 1745 to deal with the arrival of Prince Charles Edward in the Highlands, and his harsh treatment of the Scots earned him the nickname of 'Butcher' Cumberland. Although he had hoped to return to Flanders the command was given to Prince Charles of Lorraine, but he was given it back again in 1747 and it ended with the capturing of Berg-op-Zoom for the allies. On his return to England he was made Ranger of Windsor Park, and it is perhaps the uniform of this office that he is wearing.

Reynolds painted the Duke on many occasions, but there appears to be no prototype for this portrait (see A. Graves and W.V. Cronin, A Histroy of the Works of Sir Joshua Reynold, P.R.A. 1899, I, pp.. 215-8