I have the BMA book by BG Cramp, which is very informative. Namely:-
Re: South African viscounts: Mike Bishop was in Israel when he noticed in Flight Magazine the advert for the viscounts. He then went down to S.Africa and was told the fleet was to be sold as a whole and not seperately. He only had board approval to buy 2 viscounts and not 7! Unabashed he decided to offer the same cash amount he had board approval, but for all 7. As we now know, he offer was accepted and the rest is history.
Re; the german viscounts. These were never as reliable or corrosion free as the S.African ones and they appear to have less successful overall.
There's other gems in the book which is a marvellous story of an enterprising independant british airline.
airsmiles
PS: Viscounts had Dart engines, not the Tynes which were fitted to the Vanguard.