In FL, I feel like there’s a lot of unexplored worldbuilding potential around the fact that Victorian-era London has openly nonbinary individuals as part of society and no one questions it. There are a few mentions of the attitudes of the day towards women, but none about how society feels towards people outside the binary. Presumably the fact that London is effectively ruled by twelve pointedly genderless individuals (almost sarcastic assumption of “Mr” aside) forced people to adapt.
I imagine shortly after the fall, it became something of a fad for people to dress in long brown cloaks and become indignant at personal questions. It began as a fashion statement or piece of performance art, but some used it as cover to assert their identities. And when they started appearing as such in professional settings, society was rankled, but they couldn’t question it without raising the ire of the Masters (at least one poor fool is rotting in the darkest corner of New Newgate because they didn’t realize they were speaking to an actual Master). Shortly, it became commonplace for people to take on the role without the attire, and from there we arrived at individuals of mysterious and indistinct gender as they are today.
There’s a lot more to be written here, but basically I feel like in the various points where it comes up “men do this, women do that”, there should be an addendum “and people who aren’t either do the other thing.” (i.e. “women call it he, men call it she” re: the Bazaar, whether to take ‘cigars and brandy’ with the men or ‘confidences and sherry’ with the ladies at a party, etc)