the staffordshire wildlfie trust have a good system, very easy to follow and includes the leaflets to advertise the local trust.
Shropshire wildlfie trust talked to me ages ago but have since not responded to any attempts at contact, i passed the details onto the wombles ages ago i dont think they had much more success.
Id say that pointing the national body at these exisitng agreements and permission systems would be a good thing, the wardens will see any cache trails and cachers at some point. Indeed the staffordshire warden at loynton moss was aware of one cache bordering thier land.
Good luck
"If you can't be a good example, then you'll just have to serve as a horrible warning."