Book excerpt: 'An incredible story crackling with royal passion, envy, ambition and betrayal ... Field's account of the psychological power play between Queen Anne and her confidante is surely definitive. A tour de force' Lucy Worsley Sarah Churchill, Duchess of Marlborough, was as glamorous as she was controversial. Politically influential and independently powerful, she was an intimate, and then a blackmailer, of Queen Anne, accusing her of keeping lesbian favourites - including Sarah's own cousin Abigail Masham. Ophelia Field's masterly biography brings Sarah Churchill's own voice, passionate and intelligent, back to life. Here is an unforgettable portrait of a woman who cared intensely about how we would remember her - perfect for fans interested in the history behind the major motion picture starring Rachel Weisz with Olivia Colman and Emma Stone.