@LTNman (or anyone)
The old Spittlesea Hospital Main Building (now used by SixT) has to be the oldest original building on the site but what can you tell us about Hangar 24?
I'd hazard a guess that it's very much the last man standing in term of oldest airport buildings. (there is/was a photo of it being built somewhere in this forum). Is it now a listed building? Was it of any significance?