This hangar was mentioned in the 'Japanese pillbox at Diamond Hill' place, but deserves its own entry. It is clear to see on the satellite photo above.
Here are the notes so far:
A recent copy of HK magazine had an article 'Tearing up the town' about historical areas that may be redeveloped and disappear. Their description of Tai Hom Village, Diamond Hill says:
Also in the area is the former RAF Hangar (Grade-III), which was used by the Japanese to store jets [I think they mean 'store aeroplanes'] and other machinery following their occupation of the territory.
A reader sent in a link to a photo of the area before the village was cleared. The rusty construction in the centre-left of the photo is the hangar: http://www1.uwants.com/viewthread.php?tid=5835800&extra=&highlight=%A4j%EA%A9%A7%F8&page=1
[The pillbox was] for protecting the Japanese plane hangers, which is located just nearby in the same area.(the British hangers were located rather seaside, at the south-west corner of then Airport) (Kai Tak airport had gradually (moved) to the south in history, in the Second World War, this place is a northern boarder of the Kai Tak Airport)
It is not clear when the hangar at Tai Hom was erected and by whom (Japanese or British). However, through aerial reconnaisance photos prior to the end of WWII it is now known that the hangar was already erected in situ and would have definitely been used by the Japanese. After the war, the RAF used the hangar for their Spitfires. As the hangar was situated outside the confines of RAF Kai Tak, access to it was via a narrow road that crossed the Kai Tak Airport perimeter road (Choi Hung Road).
The Mapping of Hong Kong book on aerial reconnaisance circa 1944 [has an aerial photo which] shows the hangar and the access road traversing the ring road i.e Clearwater Bay Road, subsequently renamed Choi Hung Road.The 1945-1958 Kai Tak Airport comprised two paved crossing runways that were built by the Japanese with British POW labour. The main runway in similar direction to the reclaimed runway at Kai Tak was located in the area that we know today as San Po Kong.
Also see this timeline of maps of the Kai Tak area, to see how the hangar was once close to the airfield.