The Duke of Devonshires Flying Childers James Seymour (1702-1752)

The picture has something of this: horse, mammal, cavalry, animal, mare, stallion, equestrian, equine, farm, mane, livestock, seated, gallop, grass, pasture, bridle, pony, field, chestnut, racehorse.
Perhaps it’s a painting of a man standing next to a brown horse with a bridle on it’s head and.