Just had a video popup in my YouTube subscription list by a guy called Martin Zero.It's all about The Butterley Gangroad and other hidden Derbyshire tunnels and railways dating back from the 1790's.
Whats really interesting (to me) is the "mechanical horse" Featured about 13min 40 seconds. I wonder if anyone has tried to model it?
**LINK**
Really interesting amateur historical video. Certainly better than the drivel on TV