Kate Ross' regency historical mysteries are lovely, although the hero is male. Unfortunately there are only four of them because she died. (Edit: I should totally reread those. It's been an age.)

Not mystery, but if you haven't read Joanna Bourne's historical spy novels they are excellent.

Brother Cadfael? Miss Silver?

Couldn't get into Brother Cadfael, but will check the others out...

An Unsuitable Job for a Woman?

I will definitely second the Joanna Bourne's Spymaster series and Elizabeth Peter's Amelia Peabody books (except for the last one which was published posthumously this year - shudder).

Ariana Franklin wrote some medieval mysteries that are good - set during the reign of Henry II, the detective is a woman doctor. The first book is "Mistress of the Art of Death".

You might also like Kerry Greenwood's Phryne Fisher books - Australia in the 1920s. The detective is a very liberated woman. Good TV series as well.

A different take on the "no you shouldn't be working on this" detective is Barbara Hambly's Benjamin January series. He's a free man of color in New Orleans in the 1830s. She does a very good job of conveying how very carefully a black man, regardless of how free, had to walk to stay alive and safe much less investigate a death.

I enjoyed the Benjamin January series ... in a horrifying sort of way. You might try the "Study in Scarlet Women" and "A Conspiracy in Belgravia" - kind of turns the Sherlock Holmes stories on their head.

I recently finished Jane Steele - it's inspired by Jane Eyre, but early in the book Jane says, "Reader, I murdered him." And goes on from there. It's written in the style of a Victorian novel, so it can be kind of slow going, but it's good.

published posthumously

Oh, she's dead? Well, she was getting up there. I always enjoyed the anthropology books she wrote under her real name, Barbara Mertz. She also wrote decent mysteries--though more typical of the genre of "woman in peril solves mystery and finds love"--under the name Barbara Michaels. But I've always like her versions better than others.

Thanks—lady doctor sounds totally up my alley. And I definitely enjoyed Study in Scarlet Women and the sequel.

Connie - Yes, alas. She died in 2013. The last book, "The Painted Queen", was completed by Joan Hess and I found it pretty much unreadable. The characters were off and the villains of the week were just annoying.

Anne Perry's Charlotte and Thomas Pitt series, set in Victorian London, is also a lot of fun, especially in the beginning. And her William Monk series is also good, and features an aristocratically born woman named Hester who becomes a nurse during the Crimean War.

I loved the Benjamin January books.