As far as the tune is concerned. If my memory serves me correctly, the tune is included in a book called 'The Drummers' and Fifers' Guide,' by Geo. B. Bruce and Dan D. Emmett, which was published in 1865. If I get time I'll try to dig it out and see what the tune was called in the 19th century. As far as which came first, Edmund Fitzgerald or Back Home in Derry. I had alway been led to understand, that the Edmund Fitzgerald tune was used purposly to get Back Home in Derry air time, which seems to have worked.