One difficulty with my suggestion of "Don't Send My Boy to Prison" is that I haven't found the melody except on a couple of old 20's records that I remember. What was the original tune used in the music hall?
Can Malcolm Douglas or someone else from the UK come up with it?

As it stands, the tune(s) is(are) so simple that I would not doubt someone who called it an old Roman song, "Don't send my boy to fight the Gauls."