Thank you, Malcolm! I've long wanted to find out whether that song was actually written by Colin Wilkie. I have a McCalmans recording where they don't seem to know.
I had no idea either it was about a German mining disaster. This must have been at Lengede. I remember vividly sitting glued to my gran's set in those days in 1963 to follow the rescue operations shown live on TV. They were actually able to rescue several miners by hauling them up one by one in a metal capsule through a specially drilled shaft, days after they'd been given up for dead. It's known as the 'Lengede miracle' to this day.