Anyone running campaigns based in London in any era may be interested in this article:
This relates to "Jack Cades" Cavern in Blackheath as discussed in the London Guidebook. For people running present day campaigns they may be interested to know the main A2 road over the caverns collapsed about a 18 months ago to 2 years ago and they are still investigating what caused it.
If anyone wants additional local information post back to me on this site with requests as I live right next to where the caverns are supposed to be located. I will reply presuming the tentacles don't get me first!