] There were plenty of "conduct books" around that laid out many rules and regualtions about what one should, or should not do.

The conduct books were full of advice to the upwardly mobile on how to appear like the already up. So, what would be a rule in a conduct book would be, for the top people, more like a description of how they acted. People like Mr Darcy and Lady Catherine would take no notice of the rules, and if they wanted to talk with their mouths stuffed, would talk and stuff away.

On the other hand, good manners in most societies rules out spraying your eating companions with gobbets of food, so over-stuffing would propably be out.

One thing I'm sure of, though. Wiping your mouth on the tablecloth, as Mr Bennet does in P&P, was unacceptable in most society.