The Apedale underground tour takes place in a former "small mine", with most of the old workings sealed off. If I remember correctly you walk down a 1:4 dip before turning off to a selection of galleries depicting various mining schemes (shotfiring, a pit bottom, etc.). You then walk up the return dip (again 1:4) to the surface.
Although there is a "mine manager" and inspections have to take place before the public are allowed underground, there is some form of dispensation from the Inspectorate with allows cameras, digital watches, etc, to be taken underground. Thats why it proves popular for film crews, I think the BBC used it for parts of the recent Survivors series (not 100% sure but it looked like it).
'where's the shearer?'[center]