Lots of confusion here I know, which I will attempt to clarify with the DNPA. Please copy me in on any relevant emails as that will help and I will feed back any information that I get on to this web site.
The new DNPA guidelines were obviously put together as a combination of the standard Groundspeak rules and the existing letterboxing guidelines. To clarify muddypuddles point above about “all caches” or just “SSSI caches” the Groundspeak guidelines say “You assure us that you have the landowner’s and/or land manager’s permission before you hide any geocache, whether placed on private or public property.” This is nothing new and has just been incorporated into the DNPA guidelines. Both guidelines also say that all caches should be labelled as such and I have seen many recent caches that have no label at all saying they are geocaches.
I would imagine that 80% of caches placed in the UK do NOT have landowners permission, but we were given dispensation from this rule with the previous GAGB land agreement.