Out of interest, how detailed is it on Ceunant Ddu? (rather than Foel Grochan and Hen Gloddfa)
I read that Ceunant Ddu was connected to Abercorris and at one point, parts were worked from Abercorris, which sounds unlikely... but read in the gazetteer. If true that'd be an interesting through trip, assuming it's not flooded then collapsed.
Are there many clues in the book to confirm/deny that, if so I'd order a copy