These must have existed in some quantity as mine is not the only one around. There were at least two others I was aware of in the UK. My example actually came out of Canada during a trade. The QC on the label was thought to be a both-up attempt to re-label a postwar blouse. Needless to say, quite a surprise when a wartime-pattern blouse showed up.
Some subtle changes between it and the later issue Aircrew Blouse but all-in-all very similar. The 1939-dated example I saw was the same. I've been looking to see if I have any pics of the label and blouse. This was pre-digital cameras (at my house, anyway) so likely a print floating around somewhere.
Again, I believe these were test issues. It would make sense to have aircrew wearing them since that was the projected end-user at the time. I thought I read reference to these being tested outside the immediate combat area (11/12 Group) but am not sure??