Hi, L-Man- Here (click) is the main discussion of the Roddy McCorley tune. Although the later song, "Sean, South Of Garryowen," uses the same tune, it appears that "Sean" got the tune from "Roddy McCorley" - rather than the other way around. As the thread says, the early source of the tune is unknown.
Let's keep the discussion in that thread.
I'm going to close this thread and move our messages to the existing thread.
-Joe-