"Atkinson's tunnel entrance would be re-opened and a new tunnel constructed to the centre of the hill, ideally wholly within the line of the original. Then working outwards from the centre, the remaining collapse and infill material would be removed and all voids re-filled with properly compacted chalk.

This technique could cause more stratigraphic loss than remote filling. There is the risk that new workings may trigger further collapse."

It follows from this that the envisaged tunnel will be larger than Atkinson's and quite independent of it - not even necessarily being coextensive with it.

Furthermore, it will be a "tunnel - plus" since the voids which lie adjacent to it will also have to be packed manually and there's the likelihood of further collapses/ enlargements of these wherever the material is loose, at a level of risk that is confirmed as unknown.

Indeed, the risk could not and will not be known further, as I was told in no uncertain terms when I put the question at the Peer Group Review. I got the impression it was thought I had a damn cheek to be complaining that the risk assessment expressed such little precision about the risk.

On this basis, the concept of a nice regular tunnel is misleading. It will be such a tunnel contained within a larger zone of surrounding collapsed sections of size and shape that will be unknown until they happen.