As well as the radio flying at the former Croydon Airport there is also a paved control-line circle which is used by the British F2A CL World Championships speed team for practice; around 300km/hr from a 2.5 c.c. engine running at 36,000 rpm. In the 1950s the airport was the scene of Buster's conversion onto Tiger Moths after a flying scholarship at Redhill with Magisters. I still have the helmet, complete with Gosport tubes. Happy days.