The Gold Mine model (3 of the 5 panels) is currently being exhibited in the Royal Academy Summer Show, in the Large Weston room curated by Ian Ritchie RA.
Harry Hill sums the whole enterprise up nicely:
"This looks a bit like the set of a Bond movie; you can imagine the head of SMERCH having his office up in the top, and then he’s got his missile down this hole, trained on Buckingham Palace. This would be nice to have in an out-house, if you lived somewhere big, then you could set your trains or your Scalextric up around it." - Harry Hill
https://se.royalacademy.org.uk/tour/Harry-Hill/15/8
https://player.vimeo.com/video/129245899