(UTC)

REVISED UPDATE: As far as I can tell, "Hen Wlad Fy Nhadau" does not now appear on any list of anthems, national or otherwise. The links given above take you to List of anthems of UN member states, which has no mention of it, or National anthem, which has this little gem:
===For parts of states===
The Soviet Union and the United Kingdom, amongst others, are notionally held to be unions of many "nations" by various definitions. Each of the different nations may have their own "national anthem" and these songs may be officially recognized.
14 of the 15 republics of the Soviet Union had their own official song which was used at events connected to that republic. The Russian republic used the USSR's national anthem. Some republics retained the melodies of those songs after the dissolution of the USSR (see the article National anthems of the Soviet Union and Union Republics).
The United Kingdom's national anthem is "God Save the Queen" but its constituent countries also have their own anthems which have varying degrees of official recognition. England, Scotland, Wales and Northern Ireland each have a number of songs which may be played at occasions such as sports matches and official events. The song usually played for England is "God Save the Queen", though sometimes Jerusalem and Land of Hope and Glory may be played instead. Scotland has relatively recently adopted Flower of Scotland as its unofficial National Anthem, while Wales has sung Mae Hen Wlad Fy Nhadau (Land Of My Fathers) since the 19th century. Northern Ireland too has traditionally used "God Save the Queen" though Londonderry Air is also used.
"Wales has sung Mae Hen Wlad Fy Nhadau (Land Of My Fathers) since the 19th century", which is pretty good going - was it non-stop? No mention of the term "national anthem" and the wording of the intro - notionally held to be unions of many "nations" by various definitions. Each of the different nations may have their own "national anthem" - plus the section heading "parts of states" - clearly downgrades the status of Wales (and others). But my main concern is that our national anthem gets no recognition on a list, unless I've missed it; nothing showed on 'what links here'.   22:55, 4 September 2009