Turret Trainer-y type thing, anyone recognise it?

Can anyone shed any light on what this building might be, please?




It's from Site 13 at RAF Thurleigh, which was the 40th CBW.
That site had Decontams and Barrack huts and a Mess. It was originally a WAAF area.


This particular building is not extant on WW2 photos as far as I can tell, nor is it on the RSP, but was there in the 50s until its removal post mid-80s.


Mid-80s, a better view from the commissioning of the 306th Memorial next to it.


I had thought it might be a Turret Trainer but it would be in the wrong place, and anyway the side that should have thumping great doors, doesn't.
Squash Court/Gym? Even though those were in the Ancilliary area, Site 2.
I'm trying to work out what it was, and if it was something that may have been added to the base after my (undated) aerial photos.
If anyone can help, much obliged.