In reply to Sl@te Head:
To be fair, "Union rock" is a pretty direct and meaningful translation of "Craig yr undeb"; I can't see a problem in calling it that on an (english language) forum, especially as it may then convey more sense of the local historical significance to visitors who don't 'siarad cymraeg'.
"Lion rock" I agree is a rather "Disney-fied" name for the crags around the village of Fachwen, and does not have any correlation with local names.
Not helped by the fact that duplicate entries with different names (Union rock, Yellow wall, Lion Rocks etc.) appear in the UKC logbooks......
Post edited at 22:38