What’s the story regarding the downstream sump at Black Shiver ? There is a line in situ there. How did the exploration go?

Glad he inspired you with caving. Arthur's maps were very good. I have his Gaping Gill map from 1952 framed on my wall that he drew for the Cave Research Group. Black Shiver is a fantastic caving trip. You are right about the return out of Black Dub. Leaving a long tail would certainly help...