I enquired of most everyone about gentlemen's clothing of the 1760s; and other mannerisms, and ended up spending a lot of time with a... musician is too loose a term. A maestro of period music. At one point he took out a 19th century violin from his cart, pointed out the differences between it and a modern violin, and played a very complicated melody. It wasn't even his primary instrument! He had a German flute, rare reproductions of 18th & 19th century music books, and a custom made pushcart with an awning to protect everything. Period music was obviously his overriding passion. Anyway, I asked him about clothes, and one thing he showed me was a pin.
A heart, with the point twisted to one side, and a crown of garnets.
"Most people wouldn't think to show you this," he said. "It's hidden under layers. But men's shirts were open-fronted and this held them closed."
He was wearing, he added naturally, an antique pin, and gave me the rest of the lore. "The Witch's Heart" was an English charm against witchcraft in the 1600s- early 1700s, similar to the Scottish Luckenbooth. It was pinned to baby blankets and baby clothes; infant mortality rates were high and people were superstitious. By 1800 it had become more of a lover's token, signifying "You have enchanted me."
I mean! A 200 year-old pin for his costume! And no one would even see it! THAT is being in character~!
I went home and drafted a chapter about it, I was so inspired. It's been reduced to this one page, unfortunately. If I ever redraw/rewrite this story from the beginning (it needs it!) it might get that chapter back. It has potent symbolism, but so does the pocket watch, and I'd have to time it more carefully so they're not competing for attention in the same chapter.
Finally I was able to share that story! By summer perhaps I will be able to share the REASON this is set in the very particular year of 1761......