Portrait of a Man, Probably a Self-Portrait Hugh Barron (1745-1791)

The picture has something of this: people, portrait, music, royalty, wear, man, military uniform, leader, retro, musician, monarch, facial hair, mustache, vest, sash.
Perhaps it’s a painting of a man holding a violin in his right hand and a book in his left hand, in front of him is a portrait of him.