Owned by one of Napoleon’s most brilliant generals and then the founder of the world’s first news agency, the story of Breguet No. 217 — one of only two watches of its kind from the very rare perpétuelle series — is extraordinary. Regarded as one of Abraham-Louis Breguet’s masterpieces, the reappearance of this exceptional perpétuelle watch after decades in an important private collection provides devotees with the opportunity to obtain one of the most complicated and desirable watches ever made. Its remarkable provenance includes one of Napoleon’s generals — later a rival — and Charles-Louis Havas, the founder of Agence France-Presse (AFP), the world’s first news agency. In addition to being from the self-winding or perpétuelle series, a great rarity in itself, Breguet No. 217 has the extra complications of both day and month calendar, power reserve and, most unusually and importantly, an equation of time indication. The equation of time in astronomy is...