Madbob,
the chaps in the last pics are the army Air Despatchers, and their No. 1 is wearing a 'cloth hat' headset so that if we had an emergency he would be in the loop.
When I first started on Hastings we only had 'cloth hats ' but wore bone domes on top and parachutes for appropriate drops. If you look back at my two B/W pics from El Adem you can see the then current fashion. This carried over to the 'K' when it came into service, but for many drops we used the standard headset and boom mike. I have been retired for a long time now so do not know what the current SOP is.
Hope this helps.