Smoke Free flights started trials in 1990, but it wasn't until comparatively recently, 1998, that all flights were smoke free aboard BA.
If you like nostalgia threads, this one about TWA is about the best available on here, though sadly not all the photos are still visible:
http://www.flyertalk.com/forum/trip-...-old-days.html
The American Airlines Coach Lounge gives you an idea of what might have been: