I am new on here, but attempting to research general WW 2 information on aerodromes, rules, obstruction lighting, incidents and crashes at, etc. Yes, I understand that some official publications and Reports with Air Ministry Archives or Adastral Library Withdrawn stamped in them were sold off. Missing items in Air Ministry files "transferred to Library" seem to have disappeared, unless you are very lucky to find the missing or duplicate pieces in AIR 20.
The TNA, ought to have kept their Library complete, but it seems to have been reduced to make room for the Family History Researchers.
I agree that occasionly the file title does not seem to resemble what it contains. I have been tracing files by their original A.M. Registry number references found in other files and had some success, but this has now stopped, since TNA prevented users from interrogating the catalogue direct from the Google search bar and the original A.M. file numbers cannot always be found from the L/H search box, because you have to put them exactly as written and when the PRO files were entered on the electronic catalogue some bright spark put the original A.M. file reference together with the Air Ministry Historical Branch and you have to know both exactly as written.
The TNA Catalogue download facility by subject is reasonable, where you can print the list of returns off at home, gives A.M. file refs., unless the file has been broken up prior to release. But some WW 2 Committee and Sub-Committee which were in existence at the time, don't seem to have any Committee Minutes or Reports files, as though the Committee did not exist, but some may be in the CAB PREM (P.M.) series and with other papers, making them difficult to find and a long trawl.
I first visited PRO / TNA about a decade ago, but don't go much now and I feel that the Air Ministry files about Aerodromes are poor in number compared with other Aviation subjects and the only reason I can think of, was that there were probably thousands of accidents at aerodromes and the MoD either have them on extended closure or might have tipped some.
My local newpaper stated a few years ago that the Military Record Office archives holds 20 million pieces, 13 million of which are files back to WW 1. According to Hansard, during the indexing process of the Hayes Archives (Military Record Office) before transfer to Swadlincote, they had at that point indexed 11 million files. But they can't find anything you ask for, even under FOI and they make the assumption the file has been destroyed.
According to a PRO brochure written by a PRO Record Manager and once available online the Military Record Office at Hayes was once run by the PRO, which satisfied the 30 year rule. However, the MoD re-took control of the Military Records Office at Hayes in the 1990s and around 2005 transferred it to TNT Archives.
If the Air docs were withdrawn from TNA by the Government Dept, you would probably find that some files might disappear from circulation, as the reviewers who decide if a file can be released appear to be more strict since the 1990s, I had a 1991 released file photocopied and parts had been transferred to part V and when I found part V they were missing. Although after much searching, I have found most of the missing pieces in the 'mirror' files of the other Commands and Air Ministry to whom they were corresponding, with a few pieces in a file in Air 20.