From: Etiquette: The Blue Book of Social Usage by Emily Post, New York and London, Funk & Wagnalls Co, 1922/37.
The Late Guest
A polite hostess waits twenty minutes at most after the dinner hour, and then orders dinner to be served. To wait more than twenty minutes, or actually fifteen after those who took the allowable five minutes’ grace, would be showing lack of consideration to many for the sake of one. When one late guest finally enters the dining-room, it is she who must go up to the hostess and apologize for being late. The hostess remains seated and the guest merely shakes hands quickly in order that all the men at the table need not rise. The hostess must never take the guest to task, but should say something polite and conciliatory such as: “I was sure you would not want us to wait dinner!”
The ideal guest not only tries to wear becoming clothes, but tries to get into an equally becoming frame of mind. No one is ever asked out very much who is in the habit of telling people all the misfortunes and ailments she has experienced or witnessed, though the perfect guest listens with apparent sympathy to everyone else’s. Another attribute of the perfect guest is never to keep people waiting.
Formal invitations are always addressed to Mr. Stanley Smith. All other personal letters may be addressed to Stanley Smith, Esq. The title of Esquire was formerly used to denote the eldest son of a knight or members of a younger branch of a noble house. Later all graduates of universities, professional and literary men, and important landholders were given the right to this title, which even today denotes a man of education – a gentleman. John Smith, Esquire, is John Smith, Gentleman. Mr. John Smith may be a gentleman or may not be one. And yet, as noted above, all engraved initiations are addressed to “Mr.”.