Well, in the UU "Singing the Living Tradition", the credits for Morning are: Words: Eleanor Jarjcon, 1881-1965, used by permission of David Higham Assoc., Ltd. Mewsic: Gaelic melody, copyright(little c in circle)1931 Oxford University Press, harmony by david Evans, 1874-1948.

Whatever, whoever, whenever its origins, it's a good tune and song!