english original missing

I came across this message when reviewing recent changes to cy - user Xxglennxx had changed this message. I imagine that he had run a search for the word 'gwylio' - there is a whole batch of changes related to this word.

Well, I know that you can also sometimes come across unused messages through an {{Identical}} template. But since that's a template hack at the moment anyway, the proper solution should probably solve this problem.