It's a poem from D.M. MacKenzie, probably from his book Highland Readings (Glasgow: Laidlaw & MacKenzie, 1935) - which I don't have and I can't find an online table of contents.

It is recited only, by Mary B. Maclean on a 1930 shellac record, by Willie Scott on Tobar an Dualchais, and by Willie's son Sandy Scott on Folkways.

Roud seems to have given the number 5692 to both The Irthing Water Hounds and to McAllister Dances Before the King, which seems to be a mistake.

Spelling: All versions on poetry websites, as well as the Folkways album habe the spelling "McAllister", so I think this may be the original spelling.   Mary B. Maclean's record has "McAlister", Tobar an Dualchais has "MacAllister" and Alison McMorland's book (and the DT liyrics) has "MacAlister".