Do you have any real proof that it is an issue? Your 'elephant'...

Do you have any real proof that it is an issue? Your 'elephant' is pure speculation All that was over 100 years ago and the topography, infrastructure, etc could be different. Not to mention technology.

All of this stuff would have been assessed at the feasability stage before the mine was purchased. Water ingress is a very basic assessment factor along with a raft of other standard factors. Same as a house purchase, you'd be a fool to not do a flood search. NTL would have this under control.

As a non holder, I assume you are looking to downramp and pick up some cheapies?