On the McKellar album, the song is attributed to MacLeod and Kennedy-Fraser (no other information).

Last night by the shieling was Mary, my beloved.
Out on the hillside by the shieling, Mo Mary, my beloved.
Mo Mary, mo lennan, mo Mary, my beloved,
On the hillside by the shieling, mo Mary, my beloved.

Like the white lily blooming, in the peat bags dark water.
You are white as the lily, in the peat bags dark water.
Mo Mary, mo lennan, mo Mary, my beloved,
Like the white lily floating on the peat bags dark water.

Like the blue gentian blooming, wet with dew in the sunshine,
Are the eyes of my Mary, purple blue in the sunshine.
Mo Mary, mo lennan, Mo Mary, my beloved,
Lily white, blue gentian eyes, is mo Mary, My beloved.

I would like to know more about this beautiful song.
Sorcha?