Yes, it's a traditional English "Barrel Hand Protector", made in England. Made of spring steel, leather covered inside and out. I forgot where and when I bought it, probably in some English gunshop many years ago. It slides on the barrels, leaving the top open. I found these first mentioned in the 1912 Westley Richards catalog. Quite practical as I shoot the gun Robert Churchill style, left hand well before the splinter foreend.
When I was a teen, I read a German translation of Robert Churchill's book on shotgun shooting and learned a lot. Since then I wanted to have a real Churchill, but they were far beyond my price range. This AYA was the closest thing I could afford and it served me well all those years.