Marguerite Françoise Bouvier de la Mothe de Cepoy (1767–1808), known as Countess de Buffon, was a French noble, known as the royal mistress of Louis Philippe II, Duke of Orléans from 1784 until 1793.Mémoires de la Comtesse de Boigne, née d'Osmond, Paris, Mercure de France, 1971 – Tome 1, p. 165
She was the daughter of marquis Guillaume François de Cepoy and Élisabeth Amaranthe Jogues de Martinville and married Count Georges Louis Marie Leclerc de Buffon (1764-1794) in 1784; the same year, she became the lover of Orléans, with whom she had a son, Count Victor du Buffon (1792-1812). During the Terror, she helped the legitimate sons of Orléans escape prison. In 1794, she divorced and emigrated to England, where she became a supporter of Louis Philippe.
She was hosting a dinner party with Orleans when a mob presented the severed head of Marie Thérèse Louise of Savoy, Princesse de Lamballe, Buffon screamed and exclaimed that, "O God! They will carry my head like that someday!" https://archive.spectator.co.uk/article/17th-april-1897/21/the-princesse-de-lamballe
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