Bare-knuckle boxing was widespread and popular until the Marquess of Queensbury Rules of 1867 made the use of gloves obligatory. Holding and throwing opponents were both permitted under earlier rules, established in 1743 by a fighter called Jack Boughton. Under those rules there was no break in fighting, like modern breaks between rounds, until one of the boxers went down - either knocked down or thrown down. It is enjoying a revived popularity today with knuckles just taped rather than gloved.
Byron was apparently a good boxer whilst at Harrow, and remained an enthusiast throughout his life. He took lessons and sparred with one of the most celebrated boxers of the time, John ‘Gentleman’ Jackson, who had a fashionable "studio" in Bond Street where men of all social classes used to go for lessons and sparring sessions. Byron called him the "Emperor of Pugilism", and even invited him to visit Newstead Abbey.
Byron paid £250 for the screen, which has portraits of several well-known boxers and boxing scenes. The boxer to the right here is very obviously bare-knuckled and could possibly be Jackson himself - to judge from his gentlemanly shoes.