I've never come across badgers that could chew through bedrock Fjell.
Well done GrahamS; all yours.
Although entry at this point seems unlikely, the resurgence is of significance. It's probably the stream which is recorded as being heard rumbling at Robin Hood's Mill further up the field. There's what looks like a fault guided valley running WSW up the hillside behind RHM for a considerable distance. It would be interesting to re-investigate RHM but never been sure who farms that field to ask for permission.
I think the last time it was dug was getting on for a Century ago (early 1930s) and it was evidently inconclusive. Cavers didn't need to be quite so persistent in those days as there was still loads of wide open stuff to be had. There's some useful detail in Albert Mitchell's book "Yorkshire Caves and Potholes; North Ribblesdale" (1948 reprint), pages 10 & 11.