re the present fish pond, its small and circular with paved/slab edging, its outside the boundy fence and is obviously looked after, does seem a strange place to have one though !
This could be the Busk Memorial Pond:
Busk Memorial, R.A.E. Small lily pond and fountain with memorial plaque. In memory of Edward Teshmaker Busk, killed in a flying accident 5.11.1911. SU 869 545 0802 35
Hampshire Treasures: Volume 3 ( Hart and Rushmoor), Page 221 - Farnborough
A bit about ET Busk here:
http://www.airsciences.org.uk/FAST_B...hmakerBusk.pdf
There was another rectangular lily pond, either outside the medical centre or the nearby building the RAF used. Both were near the old control tower. I also recall being told there were fish in the large cooling(?) pond by the five metre tunnel, as well as some more in another pond on the Pyestock site.
With regard to the RAE gates, they weren't considered imposing enough when Nevil Shute's 'No Highway' was being filmed, so some more ornate ones were created. After filming, these gates were installed at the RAE Sports Ground, where the retail park is now by the A331.