The 839 series A/C came from Oman Air Force (serial 501 or 502) and had previously been a VIP A/C for the Shar of Persia.
It had been sold to a southern africa country (Botswana or Namibia or some other, I can't remember) in late 1977.
It went to Dan-Air for re-furbish but the work was never paid for, so Dan-Air decided to operate it.
An old colleague of mine, John Bates, was with it at the time.