Stu, I did some asking around and the following info. was provided by Steve Rider of the Eldon PC:
Nickergrove has two areas of interest:
1. Down the large internal shaft and along to the muddy chamber which has a
timbered shaft in floor (9m) which has now run in. It used to connect with
the Nickergrove part of the Streaks / Carlswark streamway.
2. Very end of the adit. This just keeps going in the vein and could connect
with mines up on eyam edge if anyone ever dug far enough. There was a
railway in put in by (I think) Noble, Proctor et al but eventually the dig
was left.....
Hope this helps....