In ch.53, I like the way Mrs. Bennet tells Bingley that Lydia and Wickham "are gone down to Newcastle, a place quite northward, it seems". Even I, a Canadian, know that Newcastle is in the north of England (maybe the northernmost city of all? I'm not sure). The fact that Mrs. Bennet seems to have spent 40+ years without figuring out the general location of this city, or realizing that other people would probably know it, is another subtle (and funny) example of her ignorance, IMO.