It’s a long long time since I noted some interesting (to me) uses of the term ‘pre-war’.
Here’s another, from the extremely entertaining 1927 novel Crazy Pavements by Beverley Nichols.
Nobody had spoken during this brief transit, except Maurice who had said:
‘Does my face look terribly pre-war tonight?’ and had been answered by an affirmative from both Julia and Lord William.
Maurice is an extremely camp representative of the Bright Young Things, and I doubt whether his utterance reflects common usage.