Just a few points from 'RAF Boscombe Down's Black Day'(#59)
1: Since when has it been an RAF Station? It's operated by MOD/DPA not MOD Air.
2: 500 - 510 mhz is I believe in UHF TV transmission territory - hardly suitable for confidential communications!
3: Boscombe test flying callsign is 'Gauntlet'. 'Tester' is used by the Empire Test Pilot School, and Blackbox was originally the callsign of the Radar Research Unit at Pershore, which moved to Bedford then Boscombe.