one of the old Togston Shafts has an interesting note:
"This shaft was filled in 1963 to an unknown specification. Our records also
indicate that the
R.A.F disposed of potentially explosive material in the shaft
during the 1950s. The shaft was partially removed by opencast workings and
was sealed at the base of the excavation in 1982."
So if you're at Togston one night and you hear a deep rumble and the ground shakes for a bit don't worry you know what it is.