We're Pretty Sure This Has Happened To Us A Few Times, As Well.

Mathers was deceived into passing over the secrets of the Golden Dawn to an American fraudulent medium and con artist known as Mrs. Horos, who also went under the names Mrs. Dutton, Mrs. Johnson, and Marie Louise of the Commune. Her magical motto was Swami Vive Ananda, so she was known among Golden Dawn members as Soror (Sister) S.V.A.

Mrs. Horus learned a smattering of Golden Dawn lore from members living in New York, and was able to use it to persuade the credulous Mathers that she possessed the Order rank of 8=3, Magister Templi, which was one grade higher than Mathers' own rank. The 7=3 rank of Mathers was the highest level that could be attained in the Second Order, so Mrs. Horos was claiming to belong to the Third Order of the Golden Dawn, the Argentum Astrum (Silver Star). At that time, the Third Order had no existence on the earthly plane (Crowley would later use the name for one of his own organizations). Indeed, Mrs. Horos claimed to be none other than Fraulein Anna Sprengel, the German adept who was the supposed establishing authority of the Golden Dawn in England, and the link with the mystical Secret Chiefs, spiritual beings who provided the Golden Dawn with its occult teachings and its legitimacy as a Rosicrucian order. Mathers felt obliged to pass over secret Second Order documents, which Mrs. Horos and her two associates promptly stole.

This woman, described by those who had met her as being about sixty years of age, extremely fat, with a gracious and attractive manner, was aided by her husband (whether legal or common law is not clear), who went under the name Theo Horos -- the "H." mentioned by Crowley -- and another man calling himself Dr. Rose Adams. Mrs. Horos and her husband were eventually arrested. As an explanation for her corpulent body, Mrs. Horos claimed that she had absorbed the spirit of Madame Blavatsky, the leader of the Theosophical Movement, at the death of Blavatsky. Such was Mathers' willingness to embrace the miraculous that he did not dispute this assertion. Hence Crowley's expression of disgust with the childlike credulity of his former teacher and leader.

From Donald Tyson's notes on the Goetia.