I quickly told him there was a rule against asking for autographs during press events. “Is there?” he asked with a conspiratorial smile, continuing to sign the book and impishly handing it back to me.

Terry Jones, a founding member of Monty Python’s Flyng Circus, is an avid buff of the Middle Ages, so the new cable History Channel asked him to front a series on the Crusades. In doing his research, ...