On 4 February 1922, Price with James Seymour, Eric Dingwall and William Marriott had proven the spirit photographer William Hope was a fraud during tests at the British College of Psychic Science. Price wrote in his SPR report "William Hope has been found guilty of deliberately substituting his own plates for those of a sitter ... It implies that the medium brings to the sitting a duplicate slide and faked plates for fraudulent purposes."  Price secretly marked Hope's photographic plates, and provided him with a packet of additional plates that had been covertly etched with the brand image of the Imperial Dry Plate Co. Ltd. in the knowledge that the logo would be transferred to any images created with them. Unaware that Price had tampered with his supplies, Hope then attempted to produce a number of Spirit photographs. Although Hope produced several images of spirits, none of his materials contained the Imperial Dry Plate Co. Ltd logo, or the marks that Price had put on Hope's original equipment, showing that he had exchanged prepared materials containing fake spirit images for the provided materials.  Price later re-published the Society's experiment in a pamphlet of his own called Cold Light on Spiritualistic "Phenomena" - An Experiment with the Crewe Circle. Due to the exposure of Hope and other fraudulent spiritualists, Arthur Conan Doyle led a mass resignation of eighty-four members of the Society for Psychical Research, as they believed the Society was opposed to spiritualism. Doyle threatened to have Price evicted from his laboratory and claimed if he persisted to write "sewage" about spiritualists, he would meet the same fate as Houdini. Doyle and other spiritualists attacked Price and tried for years to have Price take his pamphlet out of circulation. Price wrote "Arthur Conan Doyle and his friends abused me for years for exposing Hope."  On 7 October 1930 it was claimed by spiritualists that Eileen J. Garrett made contact with the spirit of Herbert Carmichael Irwin at a seance held with Price at the National Laboratory of Psychical Research two days after the R101 disaster, while attempting to contact the then recently deceased Arthur Conan Doyle, and discussed possible causes of the accident. The event "attracted worldwide attention", thanks to the presence of a reporter. Major Oliver Villiers, a friend of Brancker, Scott, Irwin, Colmore and others aboard the airship, participated in further seances with Garrett, at which he claimed to have contacted both Irwin and other victims. Price did not come to any definite conclusion about Garrett and the seances:  It is not my intention to discuss if the medium were really controlled by the discarnate entity of Irwin, or whether the utterances emanated from her subconscious mind or those of the sitters. "Spirit" or "trance personality" would be equally interesting explanations - and equally remarkable. There is no real evidence for either hypothesis. But it is not my intention to discuss hypotheses, but rather to put on record the detailed account of a remarkably interesting and thought-provoking experiment.  Garrett's claims have since been questioned. The magician John Booth analysed the mediumship of Garrett and the paranormal claims of R101 and considered her to be a fraud. According to Booth Garrett's notes and writings show she followed the building of the R101 and she may have been given aircraft blueprints by a technician from the airdrome. However, the researcher Melvin Harris who studied the case wrote no secret accomplice was needed as the information described in Garrett's seances were "either commonplace, easily absorbed bits and pieces, or plain gobbledegook. The so-called secret information just doesn't exist."  In 1931, the National Laboratory of Psychical Research took on its most illustrious case. PS50 was paid to the medium Helen Duncan so that she could be examined under scientific conditions. Price was sceptical of Duncan and had her perform a number of test seances. She was suspected of swallowing cheesecloth which was then regurgitated as "ectoplasm". Price had proven through analysis of a sample of ectoplasm produced by Duncan, that it was made of cheesecloth. Duncan reacted violently at attempts to X-ray her, running from the laboratory and making a scene in the street, where her husband had to restrain her, destroying the controlled nature of the test. Price wrote that Duncan had given her fake ectoplasm to her husband to hide. The ectoplasm of Duncan in another test was analysed by psychical researchers and reported to be made from egg white. According to Price:  The sight of half-a-dozen men, each with a pair of scissors waiting for the word, was amusing. It came and we all jumped. One of the doctors got hold of the stuff and secured a piece. The medium screamed and the rest of the "teleplasm" went down her throat. This time it wasn't cheese-cloth. It proved to be paper, soaked in white of egg, and folded into a flattened tube ... Could anything be more infantile than a group of grown-up men wasting time, money, and energy on the antics of a fat female crook.  Price wrote up the case in Leaves from a Psychist's Case Book (1933) in a chapter called "The Cheese-Cloth Worshippers". In his report Price published photographs of Duncan in his laboratory that revealed fake ectoplasm made from cheesecloth, rubber gloves and cut-out heads from magazine covers which she pretended to her audience were spirits. Following the report written by Price, Duncan's former maid Mary McGinlay confessed in detail to having aided Duncan in her mediumship tricks, and Duncan's husband admitted the ectoplasm materialisations to be the result of regurgitation. Later Duncan was caught cheating again pretending to be a spirit in the seance room. During Duncan's famous trial in 1944, Price gave his results as evidence for the prosecution. This time Duncan and her travelling companions, Frances Brown, Ernest and Elizabeth Homer were prosecuted and convicted. Duncan was jailed for nine months, Brown for four months and the Homers were bound over.

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