Effsee; I made the point in my comment that the name implied Irish or Scottish origins.
But let us not be politically naive. You know as well as I do that while may men, from north and south, died in both World Wars, it was not necessarily a passport to popularity for an Irish Catholic to serve the crown. I can see both points of view (ie those of the Irishman who enlisted and the nationalists who resented his gesture), but it is surely quite natural to be surprised at such a song's popular appeal in nationalist ireland.