Well let us hope the wait is worth it and the next update clarifies some of the questions that seem to remain.

For instance, Moss’s observation must have a simple yes/no answer – “It also must surely have followed that the new chalk infill lying in the low ground of the compound also would have been contaminated with seed and spore from the floodwaters?”

And your query is worth attention – I can only perceive that this is a recent event, and I’m concerned that for this arch to be displaced in this manner (and by this much) would need a distinct lateral force. I would therefore question the statement in Update 14:
“Otherwise, the geotechnical conditions within the hill remain unchanged, with the 3 separate voids all remaining stable and the remainder of the tunnel standing without any observed movements or structural changes“.

I must say your puzzlement on that particular point corresponds with my own. I read that If the collapse follows a log-rate process, as shown in Chart 1 below, then a period of 1000 years will be needed for a collapse of 0.5 x cavity diameter. but then I look at that bent steelwork and can’t help thinking it got like that in the past few years due to an enormous lateral force applied to it, perhaps lasting only a second or two. Not log-rate progress at all was it?