Sophie Charlotte (1675-1725) war eine uneheliche Tochter des Kurfürsten Ernst August von Hannover und seiner Hauptmätresse Clara (oder Klara) Elisabeth von Meysenbug (1648-1700), der Gräfin von Platen, und eine Halbschwester von Georg Ludwig (1660-1727), Kurfürst von Hannover und König von Großbritannien (als Georg I.) und der berühmten Sophie Charlotte von Hannover (1668-1705), Kurfürstin von Brandenburg und Königin in Preußen. Im Jahr 1701 wurde sie mit dem Baron Johann Adolph von Kielmansegg (1668-1717) verheiratet, dem sie zwei Kinder schenkte: Charlotte (1703-1782) und Georg Ludwig (1705-1785). Im Jahr 1722 erhob ihr königlicher Halbbruder Georg I. sie zur Gräfin von Darlington.
"Lady Darlington," says Horace Walpole, "whom I saw at my mother's in my infancy, and whom I remember by being terrified by her enormous figure, was as corpulent and ample as the Duchess of Kendal was long and emaciated. Two fierce black eyes, large and rolling beneath two lofty arched eyebrows; two acres of cheeks spread with crimson; an ocean of neck that overflowed, and was not distinguished from the lower part of her body; and no part restrained by stays - no wonder that a child dreaded such an ogress." (in: Robert Folkestone Williams: Memoirs of Sophia Dorothea, Consort of George I, Vol. 1, London 1845, p. 318).
"From another valuable authority we have a delineation a little less repulsive. 'She [Sophie Charlotte von Platen] had a greater vivacity in conversation,' observes Lady Mary Wortley Montagu, 'than ever I knew in a German of either sex. She loved reading, and had a taste for all polite learning. Her humour war easy and sociable. Her constitution inclined her to gallantry. She was well-bred and amusing in company. She knew both how to please and be pleased, and had experience enough to know it was hard to do either without money. Her unlimited expenses had left her with very little remaining, and she made what haste she could to advantage of the opinion the English had of her power with the King, by receiving the presents that were made her from all quarters; and which she knew very well must cease, when it was known that the King's idleness carried him to her lodgings, without either regard of her advice, or affection for her person, which time and very bad paint had left without any of the charms that once attracted him [man war in der Vergangenheit davon ausgegangen, seine Halbschwester wäre ebenfalls seine Mätresse gewesen, was nicht stimmt].'" (in: Robert Folkestone Williams: Memoirs of Sophia Dorothea, Consort of George I, Vol. 1, London 1845, pp. 318-319).