Galin I think that my cross post will answer that point. The Estate would not have provided access then quixotically withheld permission. Access to the letters was not theirs to grant. If you look at the Trust accounts you will see that some correspondents have returned or bequested their letters from JRRT to the estate but most letters he wrote will have stayed with the recipients as is the normal course of things. Now an interesting question might be if when a letter comes up for sale and it is photographed for sale say on E-bay if copyright is infringed if the contents can be read. NB None of the Downer legal eagles should take that as instruction since I haven't a bean!
Must pop out and then decide if I can persuade a certain terrier to yield his rat