In this final book in the trilogy, the backstory of the survival of the Tudor line becomes significant. Edward VI was still a sickly boy, but his regents included his two sisters, who, since Christianity didn't spread to Britain in this world, are not called Mary and Elizabeth but Mathilda Julia (known as Julia) and Edith. That's the kind of detail I rarely see an author think about, and I love it. Nor were they on opposite sides of a religious divide, being both Romano-Celtic-Saxon pagans, so they worked together to solve a problem in much the same style as the protagonist of this book: doing what they thought was right despite the fact that the men around them didn't want them to.
The villain is perhaps meant to evoke Napoleon, though he's the Duc de Orleans, not a commoner. I say this because he's several times described as a short man, and although Napoleon, in reality, was average height for a Frenchman of his time, he surrounded himself with large men as his personal guard, hence the enduring myth that he was unusually small. The Duc's ambition is less than that of Napoleon: it's to unite what we would think of as France, which in this world consists of a number of duchies and the like, three of which are under the control of (and part of) the Kingdom of Britain, while the rest are at odds amongst themselves. It's similar to Germany or Italy before their unifications, in other words, or France itself at a much earlier era.
The editing is excellent, with just one or two glitches (like a hyphen between an adjective and the noun it modifies at one point), far better than I usually see.
However, there are a couple of scenes where the amount of dialog and action doesn't seem to fit the stated timing. For instance, one scene begins in early afternoon. No more than three-quarters of an hour's worth of events later, it's late afternoon, and the characters decide to stop work and resume in the morning. And, since what they were setting out to do was the whole point of their expedition, why not start in the morning of the first day? There's no hint of a reason given as to why they started in the afternoon in the first place.
That's a minor fault in what is a very solid piece of writing. I will say that it didn't hold my attention quite as strongly as the previous book. Grey, despite infiltrating a military camp full of enemies, some of whom knew him and would be able to identify him as not the person he was pretending to be, never really seemed in much danger, and the fact that there were several other subplots going on at the same time as all that slowed down the progression of all of them. These books rarely achieve a sense of urgency, though they can certainly manage moments of tension. They do feel more on the cosy end of the spectrum, despite having some high stakes (usually the preservation of the political status quo against those who would overthrow it with violence). The romances are quiet and slow-burn and certainly not steamy. None of this is necessarily a criticism, because cosy is a great tone for fantasy and usually my preference, but I did feel the excitement level could have been raised a bit and that it would have improved my enjoyment of the book.
I did definitely enjoy it, though, and hope that the author will write more than just this one very fine trilogy.