Why write stories set in the past, say 1940s to the late 1970s

[TheRedChamber]

Though given being 'queer' or 'homosexual' wasn't an identity until the last century, such things were a vice. And everyone has vices. Judge not...
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Many people at the time would have agreed that such sins were between the actors and God, just don't scare the horses. Nowt so queer as folk, etc.

So you can write happy queers in such time periods, but need to understand the historical context, not plonk modern characters with their attitudes into the past.

To quote David Mitchell playing Shakespeare - "Look, I'm not gay. I just wrote 126 sonnets about my love for another man."