Sadly the Robocopp page (that's what "this page" was) is no longer around.

If you want to hear Bugeilio'r Gwenith Gwyn in Welsh, there are (in 2010) versions on YouTube by Mary Hopkin (was she Welsh?), Aled Jones and Tom Jones, eg http://www.youtube.com/watch?v=ZXpUkO600HU

Thanks for all the info, both here and at http://www.mudcat.org/thread.cfm?threadid=8424 xx