She is primarily famous, however, not in herself, but because her life was used as a canvas for a long, highly detailed and circumstantial, and in spots very funny, set of apocryphal memoirs, the Souvenirs de la Marquise de Créquy, that were in fact written by Maurice Cousin de Courchamps in the early 19th century. The work deceived many, especially among the French, but has been debunked as a very clever forgery.
Like most successful lies, it is composed for the most part of truth. Buried in endless pages of mainly accurate noble genealogies and court gossip from the reigns of Louis XIV, Louis XV, Louis XVI, and Napoleon, the Souvenirs abound in unsubstantiatable tales for which she is the sole "authority", treated in such a manner and covering such subjects as to make them irresistible in many quarters, but which are nonetheless almost certainly false. The single most commonly referred to among these stories, and the most widely believed in France, is probably her statement, with a full detailed story to back it up, that "God Save the Queen," the British national anthem, was in fact written by Lully and sung by a French girls' school to greet the French king Louis XIV; which the French editor annotates with a further story, taken from a French tabloid of 1851, that the tune was later plagiarized by Handel and sold to the British crown (Souvenirs, Vol. I, Chapter IV) The profusion of such material in the Souvenirs places its author in a select company of great forgers, alongside the author of the Historia Augusta, Annio of Viterbo, and Richard of Cirencester.