The Duke of Devonshire’s Flying Childers James Seymour (1702-1752)

The picture has something of this: cavalry, horse, seated, mammal, two, equestrian, racehorse, mare, people, stallion, equine, chestnut, bridle, animal, wear, farm, action energy, jockey, saddle.
Perhaps it’s a painting of a man holding a horse’s bridle while standing in front of.