That reminds me of my youth when I was a member of Stoke-on- Trent potholing club. The biggest system we visited was Gaping Gill on the Yorkshire Moors, a system with several entrances (all vertical shafts). We entered via Bar Pot on steel wire ladders, about 70 ft as far as I remember. After a lot of walking through passages and chambers we arrived in the spectacular Gaping Gill main chamber, a huge space with a waterfall flowing in from the surface, and a shaft going up to the surface 360 ft above.
A winch system was in place as it was (I think) Whit weekend, or Easter, so it was very popular with cavers. So it was an easy ride up to the surface with a guide wire keeping the winch out of the way of falling water.
Eric. Cheadle Hulme, Stockport.