Guest Nick, the song is not as old as you suppose. CT was in the Royal Navy in the 60s (I think) and wrote this song and others from his personal experience. He was an artificer (engineer)and served in both surface ships and D/E submarines, and all his songs from this period are larded with expressions commonly used in 'The Andrew,' the RN. Other puzzlers from 'C on a R,' 'Pussers' is pursers (belonging to the Navy) and 'Donny B' is Donnybristle(sp?) in Scotland. There are terms like this in virtually every verse.
Someone will sing his songs at virtually every festival in England, Australia, and New Zealand, and, I'm told, sometimes in the States and Canada too.
Haven't we been here before?