So... What with tending to write at the Porn end of the spectrum, I've been looking up regency (going by the uniforms in MR, that's about the right era) clothing and how it was layered.
Many (though not all) folks in menswear
didn't bother with drawers - a shirt could be a sort of all-in-one under-layer, apparently - but they did exist - most frequently used in colder weather. The original long underwear, basically.
Maybe it's not surprising that Polly was one of said folks who didn't bother (she wouldn't have had to use her belt to secure her socks, if she had) given the following: A girl - or at least someone in womenswear
- were to don drawers, she'd be thought of as a slut. (Good girls, I guess, don't lift their skirts high enough to warrent them?)
So that gals at the Solid Doves probably would have worn "smalls" or knee-length "open drawers" or some other item that was split down the middle, but - regardless of reputation - girls at the Grey House, the maids at The Dutchess, and people like Roundheels Molly wouldn't have bothered.
Polly wouldn't have had anything available in her own wardrobe to use under a pair of trousers, particularly not the fitted ones that come with the army uniform.
Someone like Blouse - meaning someone who's upper-class enough to have trousers made of something fancy
might have worn them with the dress uniform. And, yes, Mal might have as well (though I'm happy enough to skip that bit for the sake of narrative convenience).
Other points of interest:
While a lot of women wore stays (or a corset, as the term was shifting at the time) that went all the way down to the hips, "short stays" were very much an option, and made things like bending at the waist, well, possible... but getting books off of high shelves was really not going to happen. Inconveniently.
I know Polly spends a lot of time grumbling about skirts and how they catch on everything, but I'd have thought she'd be more interested in the way the lack of under-binding and its accompanying full range of motion made life a whole hell of a lot easier.
Then again, maybe - what with the fairly flat chest and all - she opted for one of those wrap-around brasier kind of things that maybe, maybe
allowed for a little more movement, given the whole working-in-an-inn situation and what that would have required with regards to getting things off of shelves and such-like. (Maybe that's why - or an extra reason why - beer mugs were kept under the bar rather than hanging above it?)
I suspect any boning in Borongravia would have been done with reeds. Partially because of the amount of poverty going on, but also because it's a very wet, river-heavy country that borders swampy Genua on one side. The lowlands, at least, would have probably had a surplus of marshes, but whalebone from the Rim Ocean (and possibly the Circle Sea) would have been very difficult to come by.
The fingerless glove that was named after Major Blouse... would have been a very
new and unusual thing, indeed. Fingerless gloves or mittens might have been worn at home, in the winter, specifically for warmth, but lace fingerless-mittens that might have been worn out didn't show up for another 50 years or so, and were (apparently) mostly a Victorian Thing. It's possible that they were meant to be some kind of "dinner glove" (normally folks took their gloves off to eat meals) or, alternatively, the whole "no fingers" thing was meant to be every-so-slightly scandalous and, as such, a bit of a nod (or possibly a bit of a smirk) towards the more-than-slightly scandalous nature of Blouse's first command.
Trivia! What fun! :-D