So why isn't Base hangar at RAF Brize Norton called "Station hangar" then?
The RAF did officially use the term base during WW2. From around 1943 onwards the various Groups within Bomber Command formed a unit known as a Base. This was a group of airfields commanded by an Air Commodore, the individual airfields being still commanded by Group Captains. An example was No.54 Base which consisted of RAF Stations Coningsby, Woodhall Spa and Metheringham.
All Bomber Command stations were so grouped. The guy in charge was known as the "Base Commander"