I've never been on a BA flight where smoking was allowed, but I do recall flying on Maersk Air from the UK to Denmark in the late 1990s and being surprised that there was still a smoking section - the rear 3 rows or so.

Maersk Air was a bit idiosyncratic, their staff were (as almost all Danes are) fluent in at least English as well as Danish but they announced in both languages "We will now do the safety demonstration in Danish only" and did so. This greatly unsettled the British passengers, although I was fine. My Danish relatives all found this as amusing as I did when I told them

They were taken over by SAS and it was all no smoking, bilingual announcements at all times and so on.