Can't remember if I mentioned it in the other thread but ... Mentra Gwen is also used to refer to that particular metre (meter?). So, I imagine you've got the right song - words and music - as they're generally the most popular in our lifetimes. (As on Contemplator ) But you'll note that they're the same meter (metre?) as Captain Kidd, Admiral Benbow, etc.

The Contemplator website also opens with another of the Mentra Gwen tunes (Dyffryn Clwyd) as an example.

Have fun.

sian