George, Marquess of Huntly (later 5th Duke of Gordon), on Tiny Benjamin Marshall (1768-1835)

The picture has something of this: cavalry, seated, mammal, horse, people, cowman, equestrian, rider, saddle, man, wear, mare, farm, action energy, motion, chestnut, animal, lid, horseback.
Perhaps it’s a painting of a man riding on the back of a brown horse next to a group of dogs and a man in a red coat and white hat.