Fred Weatherly was almost certainly thinking of the Highland pipes -though the phrase is really only a "stock" image in his song- and may not even have known that there was any other kind. He was a lawyer and songwriter, after all, and the Irish connection with Danny Boy is the tune, not the words, which were originally set to another air of Weatherly's own making, which didn't sell.

The American sets from Flanders and Scarborough above are particularly interesting in that they show clear precedents for Maguire's chorus (which I think I had supposed to be his own); unfortunately I don't have the relevant volume of Flanders, so I can't help with the tune.