Not strictly a mine, but I've been sent and thought it worth sharing.
The body that are trying to open a path through two disused railway tunnels near Bath have arranged an open day on Thursday 27th September to go through the 1 mile 69 yard long Combe Down Tunnel.
It would be the with general public and stewarded but it might be of interest to some.
For more details see:
http://www.twotunnels.org.uk/
my orders are to sit here and watch the world go by