Enjoyable M/M historical fiction with two winning leads. Leander is especially adorable as the wide-eyed American, trying to deal with his new title. Though there isn't a huge amount of sex, I really liked his relationship with Julien, and found most of the stuff about his entry into society, his earnest love of all things Arthurian, and the discovery that he's gay really well done. I also thought Kildaire did a great job with Julien's various friends and relatives and the glimpses of gay culture during the period.
Spoilers. Like others reviewers, my main quarrel was with the suspense plot that dominates the last quarter of the book. It takes a long time to play out--with Leander off-stage for the entire time. There were so many signs that Leander was in danger that Julien's weeks of waiting around London, going to balls and soirees as he wonders what's become of his lover, becomes intolerable to the reader. There is nothing unexpected about Mayfield as a villain. The main bright point was the arrival Leander's two sexy, domineering brothers. (I'd have liked more of the three alpha males trying to boss poor Leander around.)
All in all, a solid gay historical with sexy, appealing leads and strong secondary characters.