How to address a knight, and other mysteries solved

As a fiction author of historical novels, I must balance the fine line between realism and making the story easy for the modern reader. While it may be more accurate for a young couple falling in love to call each other Miss and Mister their entire courtship, that practice seems just too formal to our modern selves.
And what’s with all the etiquette? How does one know how to address anyone? So here you are, the in’s and outs of addressing a person. (I’ll deal with titled peers and their families at a later posting.)

First Names
First names were almost never used in speech, except in rare circumstances, before this century. Most sources suggest that only children who grew up together or very intimate friends ever called each other by given names.
If a child was born into a title, either courtesy or apparent, that child was often called by his title. For example, if the son was John Smith, the Earl of Wentfordshire, he was often simply called Wentfordshire, or some nickname like Went that went with the title.

According to letters and novels written at the time, married couples often used more formal terms, even in private, rather than calling each other by first names. Therefore, they were much more formal than what is commonly portrayed in historical novels. However, because of the modern reader’s expectations, I use first names (or Christian names) in my romance novel to subtly reveal a level of established intimacy to suggest growing feelings. In The Guise of a Gentleman, the heroine is appalled to find herself calling Mr. Amesbury by his given name, Jared, in her thoughts and frequently corrects herself until finally succumbing to calling him Jared.

The Honourable
"The Honourable" is a formal title which applies to younger sons of earls and all children of viscounts and barons (and the wives of those sons). However, this term is not ever used in speech…ONLY on envelopes. It is not included in the salutation of a letter. Therefore, it would be quite impossible to know, based upon and introduction, that a person holds the title of Honourable. I used the term “honorable” in The Guise of a Gentleman in an introduction as a way of a secondary character taking a jab at the hero when he introduces him to the heroine, but it would not normally be used in speech at all.
“Mr." and "Miss" weren’t used in with "The Honourable" in speech or in writing, only on the address of an envelope. The eldest Mr. Smith would be addressed thusly: "To The Honble. Mr. Smith." A letter to his wife would be "To The Honble. Mrs. Smith." If he is a younger son, he would be addressed as the Honble. Mr. John Smith and his wife, the Honble. Mrs. John Smith.

It is interesting to note that in Persuasion, Austen states:
"they had the cards of Dowager Viscountess Dalrymple, and the Hon. Miss Carteret, to be arranged wherever they might be most visible; and 'Our cousins in Laura-place,' -- 'Our cousins, Lady Dalrymple and Miss Carteret,' were talked of to everybody." (Vol. II, Chapter iv)

Apparently, using Honorable and Miss together was used on a calling card as well on an envelope.

The
"The" is a distinction only used for peers and families of peers, so baronets and knights would never use it. An Earl’s wife, for example would be the Lady Tarrington. A woman who has a title in her own right, meaning the daughter of a duke, for example, would be the Lady Eleanor Averston. The wife of a baronet or knight would be Lady Stover, but never The Lady Stover. However, if the usage is not a formal occasion, such as being presented to the queen, "The" may be dropped.

"Miss," "Mr." and "Mrs." With and Without Given Names
"Miss" used alone with a surname, refers to the eldest unmarried daughter. Other daughters would be distinguished by using their given names. For example, Miss Smythe would be the eldest daughter while Miss Mary Smythe and Miss Jane Smythe would obviously be younger daughters. Or, you could call them all the Misses Smythe. If none of her sisters are present, a younger sister would simply be called Miss Smythe.

"Mr." is used alone with a surname refers to the eldest son (of a viscount, baron, knight, or commoner). The younger brothers are called by their Christian names, like that of "Miss" in the previous example, and their wives have the same usage. , Mr. Worthington is the eldest son, and Mrs. Worthington is his wife; Mr. Thomas Worthington is a younger son, and Mrs. Thomas Worthington is his wife.

So there you have it. Next time, titles (and you probably thought this was complicated!)