Originally Posted by
Parrhresiastes
The good ole DCA had a pair of them for "navaid calibration"
Well, yes, the Department did own two HS125s, but not at the same time. Also, they were never fitted for navaid calibration. They were used for personnel transport, training, radar calibration and testing of instrument approaches and visual approach aids, among other things. The job of navaid calibration was really the province of the F27s and later F28s.
A history of VH-CAO can be found at
http://www.airwaysmuseum.com
The second, VH-JFT, came oh so close to being written off on its ferry to the UK after being sold that it's not funny. But that's another story...