The two Viscounts which operated in BOAC colours were provided by Cambrian
They were G-AMOG & G-AMON both series 701's & operated from 1972. They were indeed subsequently replaces by BMA Viscounts
I only discovered recently that BIA had the contract at one point as well- at least during 1971.
Aircraft would position BLK-PIK then operate PIK-BFS-PIK & position back PIK-BLK. This from a former BIA BLK ops bod man now living in Jersey