Chet, I think your practice is right as the law currently stands. I was hoping to see what people thought of the suggestion that the words and music should be considered a joint work. I think it creates complications.

Under English law if you arrange a public domain tune then you are still only the author of the arrangement and you cannot prevent anyone using the unadapted tune.

But if you are quick off the mark you can register yourself at the PRS so that you get 12/12ths of the performing revenues.