Yes, it's the horizontal tunnels that worry me most. The main vertical shaft can be observed and kept under control hopefully, so long as they don't let the rain in (oops, sorry - they have haven't they!) But the horixontal ones are obviously inherently in danger.

Regarding those, the surface survey detected one (possibly two) old areas of depression attributed to the collapse of old tunnels. Additionally, there was one or perhaps two (or maybe more, who knows?) internal collapses in the months following the main collapse in May 2000 (caused by the rainwater? Who knows?).

EH say the Skanska survey has revealed that the hill was basically robust (but several areas may need attention). Considering the Skanska survey proved insufficiently accurate in defining the tunnels, and more investigation is now planned, "robust" isn't a word I'd like to use and I doubt if Mr Skanska is delighted about it since it's his professional neck. It will be fascinating to see the precise context in which the report uses the word, and whether they have opined that messing about for another few years will carry no risk!