"Are all the hangars now listed buildings which someone once mentioned?"
No the hangars are not listed buildings . None of the remaining wartime buildings are listed though a few appear on the CBA Defence Of Britain database . However as a slight claim to fame I belive that Hangar 1 , a C-Type hangar , was the last of it's type to be built and that Hangar 2 , a J-Type hangar , was the first of it's type to be built ?
The work on and around Hangar 1 is certainly good too see and probably quite a financial investment by the airport too .