Miss Duncan, from Callander near Stirling, was arrested in Portsmouth alongside three members of her audience as she conducted a seance.
Miss Duncan had been invited to Portsmouth in 1941 by a local church to demonstrate her abilities of spiritual materialisation.
At a seance, she reportedly summoned the spirit of a dead sailor who lost his life alongside 800 others during the sinking of Royal Navy warship HMS Barham. It was sunk by a German U-Boat in November 1941, but only relatives of the deceased had been informed and it had not been declared officially lost until the following January. The government had chosen to keep it secret in order to mislead the enemy and maintain morale.
On 19 January, 1944 another séance in Portsmouth was interrupted by a police raid where she and three members of the audience were arrested.
She was sentenced to nine months' imprisonment. On her release in 1945, Duncan promised to stop conducting séances; however, she was arrested during another one in 1956. She died at her home in Edinburgh a short time later.
In 2008, the Scottish Parliament rejected a petition to pardon her.