I'm looking to see how a highly paid/rich apothecary/chemist/alchemist would address the royal family (king and queen, crown prince, and two princesses). He owns a large manor house that the royal family stops at during a long trip of theirs, where he feeds them and puts them up for a while. He's not nobility himself.
I've tried searching for this, but all I can find is the forms of address used during the Regency period (early 19th century).
Thanks so much!