Prior to reading this thread I had never come across the verses about any person standing on a quay.
All the versions were obviously the same song with the sort of changes
you would get through oral transmission.
Looking at that verse it appears to have been written by the same hand and
altered to suit the audience,something an E N S A entertainer might have done in WW2.
Another thought occurred to me concerning the Boys in blue defending
their flag,could they be Union soldiers from the American civil war,the
orignal song or poem being of American origin.