Originally Posted by
kcockayne
If the "Whistling Tit" is the Argosy, it was also used at Farnborough & sundry other RAF airfields.
The one based at Farnborough was used by ETPS, nothing to do with calibrating ATC equipment, but the Wyton based ones visited every 6 months/180 days to flight check the PAR until the were replaced by Andovers. I also remember one doing a commisioning flight check on our (then) new digital readout DF; we were still giving it Class A bearings when it was overhead Wyton descending to land.