Antonia Hodgson states in the Notes to The Silver Collar that she intended to write this novel from the very beginning of the Thomas Hawkins series. The Silver Collar is the fourth book in the series.
It’s 1728. Things are going well for Thomas Hawkins and his beloved Kitty Sparks, but Thomas begins to feel discontented because he is being supported by Kitty’s wealth and her pornographic bookstore. Then the couple quarrel because Thomas learns she has secretly been seeing Magistrate Gonson, who recently got him unjustly convicted of murder.
After they argue, Thomas stomps out. He returns to find out belatedly two things—Kitty is pregnant and Magistrate Gonson has conspired to help her mother, Lady VanHook, kidnap her.
Thomas knows that Kitty is terrified of her mother, whose intentions are twofold—to take over Kitty’s fortune and to torment Kitty. Finding her pregnant adds some spice. Thomas gets help from Jeremiah, a black man whose little daughter is enslaved by Lady VanHook, and from Sam and Gabriela Fleet. They find that Kitty has been incarcerated in an insane asylum, but that’s just the beginning of this fast-moving, adventurous novel.
There was one place where the pace slowed to a slog, and that was in reading Jeremiah’s letter, which was too long and went into too much extraneous detail. Hodgson created a trap for herself when she gave him speech problems, because this section would have worked much better as a dialogue. However, in all, this was an exciting entry in the series.
whatmeread 
I enjoyed this one, but I agree that Jeremiah’s letter went on for too long. I’m hoping there’ll be another book in this series soon.
I always seem to be about a year behind you on this one.