Hi,
My mum is Scottish and remembers her mum singing this song to her (my gran was born in late 18th century)...
We are also trying to find the music and words, what my mum remembers is

I passed by your window in the still of the night
The lilies were walking so still and so quiet
Although I sang softly, so no one could hear,
Good night and God Bless you, my dear

Regards
Lorna Cairney
lbimany@yahoo.co.uk