Hi sdavid
I tried contacting the photographer (kyshum) directly by PM. He replied that he is releasing the information but only to people he knows. I don't know whether the bird is somehow inaccessible (maybe private land or a difficult to reach location) or is particularly prone to disturbance from observers.
Like you, I would guess that Lam Tsuen Valley is a likely location. It is possible that the species still occurs in small numbers at Tai Mo Shan or Tai To Yan and descends to lower altitude in winter. If so, it must be very close to extinction in HK, as I am not aware of any sightings in recent years. Unfortunately, for many of us it seems that this will remain another "bird that got away".
John
