I’m old enough to remember smoking on board flights (and trains), and I’m extremely happy that those days are behind us.

I'm a smoker and I'm also glad we don't allow smoking on flights and trains.

Double decker airframes? Since you're talking about the 1950s, you're sure not referring to what I think that means (747/A380-style "double decker"). What do you mean by your statement.

Smoking on board? Yeah, as a non-smoker, that change was a major improvement. It may have done dirty to the smokers, but those are not the majority...

...orders of magnitude improvement in safety don't matter, but yeah, you could light up back then and get bit by someone's lap rat for good measure.

Choosing the 1950s as a great time for air travel seems like an odd choice, the first pressurized airliners to be used widely started in the late 1960s.

Air travel in the 1950s was done in slow propeller planes like a DC-6, which were very loud, had a low service ceiling, had a low range, weren't particularly safe, and were unattainably expensive for most people to use.

The 747 was only put in to service in 1970, the 737 in 1968.