Whose tune was it first?

So, there I was sitting in church this afternoon half listening to the hymn that was being sung when I realized that the melody was familiar...actually very familiar and not because I am a connoisseur of ecclesiastical music but rather because it is the music from "Lordship of the Isles" by Steve McDonald!  Now, I don't know who cribbed it from who but I was smiling and singing "will you go lassie go"  along to myself while the music played which made the Missus suspicious because I rarely smile in church.  Now if I could only remember the title of the hymn!