mrodoc
Well-known member
As the number of new concepts diminishes I did think of something somebody could try that would keep them occupied for a while. The idea is to get from Land's End to John o'Groats by as many underground routes as you can excluding currently active railway or traffic tunnels. You would have to divide the country into Km squares and research each one to find any underground sites. In some places it might be sea caves, in others disused mines railway or canal tunnels and in others natural caves. Twould make an interesting excercise!