According to Don Storey in his Classic Australian Television, '[Ron]McLean had formed a company called South Pacific Films (no connection to [Roger] Mirams' similarly named but now defunct company Pacific Films), and produced a pilot for a proposed series called Odyssey, which went nowhere. In July 1973 South Pacific Films embarked on their next project - a 90-minute pilot episode for Silent Number.'

Julie Kusko in a piece on McLean for the The Australian Women's Weekly 20 April, 1974 says McLean and Mirams were partners in South Pacific Films making Spyforce and Silent Number together.