People do not explain their own year
“As you know, Caroline, since the new tax…” is a writer speaking through a wig. Caroline does know. She was there for the tax. Dialogue that exists to brief the reader is audible as a briefing, and briefings end scenes. Two people talk in order to get, hide, wound, soothe or delay something. Information is a side-effect.
If a fact must reach the reader, put it where it costs someone to say it or to hear it. A debt mentioned because a creditor is in the doorway. A death mentioned because the chair at the table is empty and a child asks. A law mentioned because someone is about to break it and needs the other person to look away.
Exposition in trouble, objects, and silence
Trouble carries facts more honestly than conversation does. We learn the price of bread when someone cannot pay it, not when a maid recites the price. We learn the succession when a toast is refused. We learn a marriage is unhappy when a name is not used.
Objects are better couriers than speeches. A black-edged letter. A key to a room the wife does not enter. A dress dyed for a wedding that has been postponed, still hanging where a guest will see it. What cannot be said at dinner is often the scene: the thing everyone is not mentioning will do more work than a paragraph of explanation after the pudding.
Period diction without costume
Full archaism — forsooth, prithee, a thicket of thees — is a dialect almost nobody can sustain, and readers experience it as fancy dress. Full modernity — “I’m fine”, “whatever”, the cadence of a group text — breaks the illusion in the other direction. Aim for clean sentences with a period ear: what they metaphor, what they will not name, how rank changes who may interrupt.
Read the lines aloud. If you stumble, the reader will. If you would not believe a person said it to another person who already shares their world, cut it. A little distinctive vocabulary, used consistently, seasons a voice. A glossary in every speech buries it.
Rank is part of the grammar
Who speaks first, who may sit, who must be addressed through a third person, who is allowed a joke: these are historical facts, and they are dramatic. A servant who knows the secret and a master who will not be told it is a better engine for exposition than a friendly chat in which both parties summarise the plot.
Let status interrupt. People talk past each other because one of them is not permitted to be clear. The reader can be trusted to hear the fact inside the evasion. Trust is the difference between dialogue that can be overheard and dialogue that keeps turning to the audience.
Try this
Take one explanatory exchange and remove every line that exists to teach the reader. Move the necessary fact into an object, a refusal, or a consequence someone has to pay.