Nigel, you are probably closer to the situation than I, but I believe that you are mistaken here.

You have, I think, quoted not the title but rather part of the first line, which, translated, is "The old land of my fathers IS (mae) dear to me".

Every source I have found gives the TITLE as "Yr hen wlad fy nhadau" or just "Hen wlad fy nhadau".