Duncan was found to be in possession of a mocked-up HMS "Barham" hat-band. This apparently related to an alleged manifestation of the spirit of a dead sailor on HMS "Barham", although Duncan apparently did not know that after 1939 sailors' hat bands carried only 'H.M.S.' and did not identify their ship. She was initially arrested under section 4 of the Vagrancy Act 1824, a minor offence tried by magistrates. The authorities regarded the case as more serious, and eventually discovered section 4 of the Witchcraft Act 1735, covering fraudulent "spiritual" activity, which was triable before a jury. Charged alongside her for conspiracy to contravene this Act were Ernest and Elizabeth Homer, who operated the Psychic centre in Portsmouth, and Frances Brown, who was Duncan's agent and went with her to set up séances. There were seven counts, two of conspiracy to contravene the Witchcraft Act, two of obtaining money by false pretences, and three of the common law offence of public mischief. The prosecution may be explained by the mood of suspicion prevailing at the time: the authorities were afraid that she could continue to reveal classified information, whatever her source was. There were also concerns that she was exploiting the recently bereaved, as the Recorder noted when passing sentence.