This is a slightly tangled web, across two threads. Masato's first set of words are those which are sung today (although the third verse should read "tra bo" and "thra bo"). The robokopp words are slightly different, and I haven't actually heard that version sung. ('acw' is correct; 'oco' isn't.) The "Neu fi a'm ffydd yn ffolach" goes back to the original publication of the song in ... 1844? ... in Maria Jane Williams' collection, Ancient National Airs of Morgannwg and Gwent. I have a facsimile edition at home and will check if robokopp is more similar to that version.

MJW had the words from the son of Iolo Morgannwg. IM had written the words down and, if memory serves, claimed the Wil Hopkin connection. However, IM was, shall we say, very creative when it came to history (he was also 'inventor' of the Druid/Eisteddfod connection) and, although the song evokes the Cefn Ydfa story in all who sing it, most scholars discount the Wil Hopkins claim. Nice story though.

Many of the words are very much in the style of Morgannwg songs and poems; indeed, the third verse is a 'floater', appearing in other folksongs, to other tunes. (In fact, I think I went to a lecture once that connects the style with ancient Indian sub-continent classical poetry. I'd have to check that.)

Tune-wise, I have an interesting note at home but won't be there for a few days. I'll post it when I can. From memory, it's connected with a tune called "Y Gelynnen" (The Holly) which was popular long before 1844. It eventually came so connected with the words that it was cited as a tune for other words as "Maid of Cefn Ydfa". I think also that the first half of the tune was a traditional style used for ploughing with oxen. Which is a whole other story ...

sian