I loved her books, in particular Strong Poison and Gaudy Night. I still have quotes from them pass through my head frequently. I would have to reread them to see if you're correct.
But she wrote them as "potboilers" while her real passion was the theological stuff. Simply trying to make money.
The weird slang excerpt is something I've heard British actors affect in old movies. It's not Southern drawl.
I think the quirky, possibly neurodivergent young me found a fellow weirdo who took me away from my grim fundamentalist upbringing at least while I was lost in her novels.
So I have a very warm spot for Ms. Sayers, however good or bad her writing may have been.