The parking area outside her house had 'sunk' a bit, and been filled in, and now it has 'sunk' again, and she was all poised to have it filled again, when a helpful relative of the builder pointed out that actually, when the ground keeps disappearing in Swiss Cheese land, it might be worth investigating. So, she got the Cornish Mining guy round, and he has poked spikes into the ground, and thinks there is probably a Shaft.
So now she is being advised that she needs to get the Cornish mining people to come and drill, at a cost of two grand (plus a skip for the debris, and making good afterwards, whatever THAT is likely to involve). And her insurance company say 'do nothing as the shaft is not actually under the house' - which seems something of a leap of faith, and surely an area right outside the house and surrounded by it on two sides, that you walk past to get to the front door, is close *enough* to the house to be at the very least, something of a worry. The mining bloke has told her not to walk over it!
Note to self: find out name of insurance company so that if my Mum and her house disappear into the Shaft, I will know who to blame.