A great book to own/read would be Paul Fussell, Class. There're distinct differences in the respective behaviours of "old money" & "new money." I don't want to overreach, but my impression is that there's similar distinctions in Europe between those who've inherited titles going back to about the time of the last dinosaur, & those whose lines were created recently (like after 1520).
The book has practical uses, not the least of which are how a type of person will sit, dress, stand, speak, & shake hands. When I interviewed for a middle-upper job with a big company, I went out & found a bunch of used high-end shirts at the Goodwill, trimmed the fray at the cuff-edges, then had them professionally washed & pressed (medium starch). I not only got the job, but I scared the crap out of the execs for months because they assumed I was dropping in from Corporate to check up on 'em.
An old-line "Southrin gen-mun" is likely wearing clothing that's very neat, a few decades out of style, & a little frayed around the edges. The jewelry might be flashy, but it won't be a ring unless it's a "good" college or the Masons. The shoes are creased (i.e. comfy & practical) but blindingly polished. The pants creases are proper & fresh but not razor-edged from heavy starch. The older this man is, the more likely he's either gone tough as a dried-out boot, or has a sparkle in his eye that suggests a degree of curiosity & mischieviousness -- & one might be hiding the other.
If he walks into the room, & you've already introduced the reader to the people in it, how do they react to this gentleman's entrance? This spares the writer from having to go all God-dy, & helps involve the reader by asking them to wonder why the people act/feel the way they do.
