Hi Noel,
When I saw your mention of HS-125 VH-CAO a couple of images immediately came to mind. I don't have one in the all black livery, however the first image
is the old DCA colours from memory, even though Arnjul owned it at the time. Qantas also had a HS-125 for training at one stage.
VH-CAO on the GA Apron at Sydney in November 1981 - Owned by Arnjul
VH-CAO on the GA Apron at Essendon on 30th December 1985 - owned by Amcor