Mick and a friend took Alan and I on my one and only underground trip in the late 60s. We went in an ancient A35 van(ours) which we actually had to push up a hill. We went down Ffynnon Ddu and saw the amazing Crystal Pool and awesome stalagtites and stalagmites. Sorry about the lack of detail. We were climbers and preferred to see the sky. Mick ( my brother in law) was, as always, informative and interesting, while being in no way condescending.  Rest in peace Mick. We’ll miss you.