In case you missed my response at http://iwentdowntostjamesinfirmary.blogspot.ca/
I am re-entering it here:

According to the official records, Grainger copyrighted that song on July 12, 1928. Under copyright law of the period, he would have had to re-register the song after 28 years (after which it would remain "protected" for another 28 years), or let if fall into the public domain. So, the question is, did Grainger re-register the copyright in 1956?

It is unlikely, as he probably died before that date. Still, he could have passed the rights along to someone else. You can scan song copyright for that year by using the search term "1956 catalog of song copyright." The Library of Congress has made these records public, and you can either search them online or download them as pdf or doc files. My own search reveals that only two songs were copyrighted be a Grainger that year, and both were by the composer Percy Grainger. My opinion, therefore, is that this song is in the public domain and you can feel free to use it. Of course, you will probably want to do your own search first.