Clunes is believed to have been a native of Sutherland. He joined the 50th (West Kent) Regiment of Foot in 1790, where he became lieutenant in 1794 and captain in 1797. From 1807, he served in the Peninsular War against France under Sir John Moore. In July 1809 he was promoted to major in the 54th (West Norfolk) Regiment of Foot, and it is the uniform of this post that he is shown wearing in this portrait. This portrait is believed to have been painted between his appointment as major in 1809 and the end of his active army service around 1811-12. Raeburn’s great equestrian portraits suggest that he was familiar with similar portraits by Sir Joshua Reynolds, which he may have known through engraved reproductions.