Having been back enough days to draw breath: on the return BA flight, we were expected to wear masks throughout. There was no annoucement about this but I asked a member of CC,
they confirmed that we had to. I have no idea how much this was maintained by pax across all cabins, in 'C' it was pretty much all mask wearing.
Upon arrival, most folks continued to wear masks at Passport control and whilst waiting for bags. It may be that a few weeks of compulsory mask wearing indoors had made it the default for visitors and more so for the SA locals.