As always, for the bulk of the details relating to espionage during the Napoleonic Wars, I am deeply indebted to Elizabeth Sparrow's minutely researched work on the subject, Secret Service: British Agents in France, 1792 — 1815. For pretty much everything else, heartfelt thanks go to Dee Hendrickson and her brilliant Regency Reference Book (aka Everything You Wanted to Know About the Regency but Were Afraid to Ask), and the ever-resourceful ladies of the Beau Monde and Writing Regency, whose encyclopedic knowledge of the early nineteenth century saved Henrietta — and her author — from any number of shocking gaffes.