Seems to have been used post WWII, especially during Korean War. Location from a mapsite; certainly was around Castle Peak area
The closest place to Shenzen that is outside of the restricted area. Used to be used by the British military for listening/watching as well as for exercises.
Can be reached via roads or more interestingly by a short hike from Ho Sheung Heung.
Some old pictures: http://www.4regtra-reunion.org.uk/16005.html
Some new pictures: http://www.tripntale.com/trip/4839/ho-sheung-heung-hong-kong-20080106-t…
Some of the entries for RAF Little Sai Wan mention going to work at the listening station at the top of the Peak, called "Batty's Belvedere".
It's very close to the site of the old building, The Eyrie.
Dates and location approximate for now. [Outline added, based on the map 1960.1 Hong Kong.]
The camp appears in photos of the area from the 1940s on. IDJ writes:
That whole area was covered with Nissen Huts and military playing fields up until at least the 1970s and probably until about the time the first Cross Harbour Tunnel was built.