It's naggingly familiar, and I suspect I've played it at some time or other. It's fairly similar to The King of the Cannibal Islands (previously Vulcan's Cave, and often used for the Cumberland Reel, though it started out as a quadrille), but isn't that tune unless rather mutated. Tunes of that shape often have a stage or Assembly Rooms origin in the 19th or late 18th centuries, and the Morris certainly has a history of adopting popular songs of the day. Although I try to avoid relying much on the "feel" of tunes for clues as to their origins (such things are often very misleading), we have to start somewhere, and Jim's comment may well prove to be the way to go.