As one who lives near all of these wonderful ex-places I can confirm that Hanworth Air Park is still used regularly for flying.
Unfortunately the aircraft are now rather small, radio-controlled and make a noise far removed from their illustrious forebears.....
Still, it is good to see Hanworth still as open space, unlike Heston which is now mostly covered by the M4 Services.
Incidentally it is interesting to see how useful the internet now is at locating places by feeding their OS co-ordinates into a site such as UKstreetmap.com. Did you know that the first OS measured baseline was established and measured by General Roy in the 1780s? It was comprised of hundreds of ten foot long glass rods and was set up from Hampton to Heathrow. The end points can still be seen, represented by upended Napoleonic cannon (although the LHR one had to be moved as I believe it would otherwise have formed a rather awkward hazard in the middle of 27R). I seem to recall that Roy's measurement over the five miles or so was about six inches out according to modern survey methods!