It's quite likely that the Clancys learned it from Colm Keane of Glinsk, Connemara, not far from their home, or from Jimmy McKee of Armagh, not far from Tommy Makem's home.
Wherever they got it, they made a right pig's-ear of it.
There is a beautiful, totally different version, far more in keeping with the words, recorded by Jim McArdle from Mary Anne Carolan.
Jim Carroll