Only one I can think of was the research in New Zealand about Macra Terror. That interested me, but its a difficult research as it relies on memories. I hope it's going well.
Im still looking ! (but the excellent research done by David (damn ive forgotten his surname but he posted it all on here ) uncovered several other classmates of mine who remembered seeing it at school and successfully identified the moster as the Macra when shown photos of various Who Mosnters....
Jon P has a theory it was shown at the school then returned to NZBC and destroyed... (which may be true ) but its interesting to note that the "destroyed" entry in the TVNZ logs is written in a completely aytpical handwriting and position to the otherwise well kept ledger .
Years before either of us had seen the logs , id been told by an TVNZ employee that stuff did go walkies from storage via various methods, tip-offs to collectors , etc etc (as has been well documented with the Lion ) and one of the methods was just to swap the contents of the cans , and destroy something else entirely , or just to remove it and list it as "destroyed" in the logs....
the destruction entry for Macra is late 1974 , i think "after" the TVNZ/NZBC move to the new Avalon studios, and the mass dumpings (i think ? )
the same source told me that there was a film collector collector in the Wairarapa who was heavilly into SF shows......
and David found many people during his research who "knew" of the same collector , but the frustrating part is nobody can recall his name....!
its possible that as the 'Lion" was in storage on a wairarapa farm for a film collector who never returned to collect his stuff , that it "may" have been part of this elusive persons collection
( the Lion eventually ended up in the collection of Larry Dugan in the 80s who sold it many years later at a film fair in Napier in 1998 ....)