Always a bit surprising that BOAC gave up services to South America in the early 1950s, indeed they were short of capable aircraft at the time but they ran many other long-line services which must have been of very dubious value. After a few years of Comet service they were the ones they offered to transfer to British United to give them a bit of a kick. Meanwhile other European operators, KLM, Air France, etc, seemed fine with carrying on with the route - and at the time there were considerable British commercial interests in South America.
My hunch is that the old disdain for BSAA for having the temerity to challenge BOAC was ingrained, and they were only too happy to dump a significant amount of their former staff, influence, etc.