Well, hell. The cat just sat on the keyboard and erased a long, rambling review, so y'all should probably thank him.
In short - am torn. This book does really lovely things with women in an alternate history Cromwell-era London (featuring Olivia Cromwell and Queen Carola, like you do), with motherhood and career versus family and marriage and honor and all sorts of things. The heroine also rapes a woman who had already been raped by a mercenary while under the heroine's protection, then frees the mercenary right before his hanging after the raped woman's suicide. I think we're supposed to think that heroes are complicated, but the author went a little overboard on the "heroes do bad things" without ever showing us why our heroine was heroic in the first place.
Other disgruntlements: incredibly distant writing - very hard to get a hold of the characters. Rampant epithetism - the same character was referred to by four different monikers in half a page. (This probably didn't help at all with the distance in the writing.) And then the heroine's husband, who seemed a fairly decent fellow all around, was almost fetishistically described in his enormous, gross, greasy, snotty fatness. Did she mention he was fat? Because he was fat. When other characters would receive no physical description at all, every single one of his attributes would be modified by an adjectivial synonym for fat. And we'd hear about how he burst his seams or overflowed a chair or smeared a greasy pork chop over the rolls of fat in his face. Are you kidding me?
And yet I still give the book three stars, because the women. This passes the Bechdel test on steroids.