Hello, Sian - I happened across this thread with interest, as I am both Welsh and Cornish ancestry. I thought perhaps the tune your are looking for could by "Crugybar" - I know it as a Welsh hymn. I was going to try to find the music to see if the words fit the phrasing, but my books are all packed up in boxes, due to a major leak in the house.

I'll pass the hymn on to my mother, whose people were from Stithians, Cornwall. She will be quite pleased.

Regards,

Lesley
Kansas City