Campaigners bid to clear the 'witch' who leaked WWII secrets about sinking battleship

But the secrecy was ended within a few days when medium Helen Duncan told a couple during a seance that their son, a sailor on the ship, had appeared from the spirit world to tell them it had sunk.

Scroll down for more...

In one of the most bizarre acts of the Second World War, Mrs Duncan was accused of leaking military secrets - and became the last woman jailed as a witch in the UK.

Now campaigners want an official pardon for the Scots-born mother of six, who spent nine months in Holloway Prison, north London.

Scroll down for more...

A group of mediums have handed a petition to the Scottish Parliament, calling on it to lobby Home Secretary Jacqui Smith.

Campaigner Roberta Gordon, from Gullane, East Lothian, said: "At the time the country was paranoid about security and the evidence used against her wasn't accurate.

"It would take away the stigma from her granddaughters and the great-grandsons."

Mrs Duncan was one of Britain's best-known mediums. During her seances she produced "ectoplasm" - a stringy white substance that is supposed to give form to spirits and allow them to communicate.

Paranormal investigators denounced her as a fraud who used cheesecloth and egg whites, but her family insist she was genuine, "an ordinary woman with a gift".

Scroll down for more...

Despite the controversy, Mrs Duncan reputedly numbered Winston Churchill and George VI among her clients.

Churchill denounced the case against her as "obsolete tomfoolery" and visited her in prison.

The Barham, a 29,000-ton battleship, was hit by three German torpedoes in the Mediterranean on November 25, 1941.

The ship went down within minutes, with the loss of 861 lives. Already reeling from the Blitz, the British government decided not to make the news public, not least to keep the Germans guessing.

But Duncan, who was living in Portsmouth at the time, held a seance just days later and told how she saw a sailor with the words HMS Barham on his hatband.

He told her: "My ship is sunk". News of the revelation reached the Admiralty and she was placed under observation. But she was not arrested until January 1944.

The trial in March 1944 caused a media sensation as Mrs Duncan was accused of being a traitor.

But the prosecution struggled to back the claim and she was convicted instead under the 1735 Witchcraft Act, which had declared there could be no such thing as a medium.

She was the last person in Britain jailed under the act, which was repealed in 1951. The last person convicted, East Londoner Jane Yorke, 72, escaped with a fine in October 1944 due to her age.

Mrs Duncan died in 1956, soon after being arrested again in a police raid on a seance.

Last year the Criminal Cases Review Commission rejected a petition for her to be pardoned, saying it would not be in the public interest.