It's an RAF airfield.
Well that narrowed it down. I looked up the list of RAF Far East airfields. I was familiar with the locations of most of them, but I wondered about Sek Kong. I thought it unlikely, being in Hong Kong, but to my surprise it is the aerodrome in question.
The runway layout is worthy of a caption competiton: "Bloggs, I meant Magnetic, not True. Go and build another runway!"
Open house if correct.