What happened to items removed from among missing airmen's possessions?

I understand it was common practice during the Second World War to remove items that might cause upset to next-of-kin from the inventory of a missing airman’s possessions.

The reasons are obvious. It wouldn’t be appropriate for letters from a girlfriend, for example, to be returned to a man’s wife.

But what happened to all the other items that were removed because they might have been regarded as sensitive material: photographs or personal diaries that referred to operations for instance? I recently came across a reference to a diary being removed from among an RAAF airman’s possessions because of the “nature of its contents” and being sent to RAAF HQ in London.

Anyone have any ideas what might have happened to such items?