I am currently writing a story set in London of 1795. I am trying my best to avoid linguistic anachronisms in the dialogue, but I have had difficulty finding reliable resources regarding spoken English of the period.
I would like to know whether any modern contractions (such as don't, can't, won't, isn't, that's, it's, etc.) were ever used in informal spoken English by Londonders during that period. Obviously, if they are anachronistic to the period I would prefer to avoid using them. However, if they were in use, they would help streamline my story's dialogue considerably in many places. I am principally interested in the application of "is"-contractions and "not"-contractions.
The characters in this story are for the most part, upper-class people with varying levels of formal education — lawyers, clergy, landed gentry, nobility, royalty, etc.
(And before anyone links it, I have read "True Grit Isn't True," but that article's focus on 19th-century American literature was not directly relevant to my question, though one of its sources suggested 17th-century origins for most is-contractions and not-contractions.)