Anyone Welsh On Here?

This is going to sound really rude but what the hell does PERYGYL mean??
I've been sent some TrustTracks stuff and the kids have been asked to research PERYGYL... all they've been told is it's Welsh and it's on RoadSigns.
Any help? One forum say's it means "beware" but I couldn't follow that up, so I don't believe it. Another web translation site said there isn't such a word as "perygyl". And babelfish doesn't translate Welsh. Damn babelfish.
I'd be really grateful for any help anyone can give...