The first time I went to Llechwedd was in 1974 when our guide was an ex-miner for whom English was clearly a second language, and not one he'd fully mastered. Going back twenty years later, and inevitably things had changed: our guide was English.
It is interesting how someone telling you what "they" used to do instead of telling you what "we" used to do, subtly changes your perception of the place.
Good to see Blaenau looking a bit more prosperous though, even if it didn't seem wholly comfortable with the idea of being a tourist destination.
Check the Llechwedd Slate Caverns' website for opening times etc.