Ah, I shot from the lip with CRS.
Seamus has the poem by Plunkett AND the song on his CD, with the song attributed to Frank and Sean O'Meara, (Bardsmusic, USA)
GRACE is in the DT of course, HERE.
And the poem is posted HERE.
Seamus credits Russel Vance, Erie PA (USA) Irish Cultural Society, for help with research.