During the Boer War, Marie Lloyd donned a khaki dress; in this slightly irreverent song, she lauds "John" for signing up during the Great War - as it was then known. This recruiting song, which was written by Charles Collins and F. W. Leigh, was published by Star Music of London, 1916. It was performed regularly by Lloyd, who actually recorded it, with some basic sound effects at the beginning.
Those familiar with Marie Lloyd's double entendres (which were doubtless written with her in mind, if not to order) will notice that John becomes Cockie later in the song. Or maybe she was alluding to someone - or something - else.
Alexander Baron - London, England