Pete -- I thank you for exonerating me. Now I can walk out in daylight again.
I hesitate to stir this pot further, but isn't there a suggestion above that a song from Marlborough's day wouldn't survive into the 20th century? And isn't there a US song called 'Molly Brooks' which is a corruption of an English song --- 'Marlbrough has gone to war' --- and hasn't that got a French couisin, 'Marlbrough se va'ten guerre'. Aren't they all about the Duke of Marlborough and aren't they all still around?
Keep waltzing your matildas, lads, and stay away from billabongs.