William Joyce was hanged in 1946

Joyce, nicknamed Lord Haw Haw because of the sneering manner of his speech, became a reviled broadcaster of English language programmes for the Nazi propaganda ministry.

"Lady Haw-Haw" also broadcast over the airwaves in her distinctive London-Mancunian accent.

They were both captured after the war and Joyce, 40, was tried and found guilty of treason.

He was hanged in 1946, while his wife awaited trial in Holloway Prison.

'Treasonable activities'

But Captain W Skardon, her legendary MI5 interrogator, showed the compassionate side of the security services in the files just made public.

He dropped proceedings against the traitor, who "submitted meekly to treatment meted out to her during her detention".

He wrote in a top secret memo: "There is no lack of evidence implicating her in the treasonable activities of her late husband, but the authorities do not think that she need be punished further."

Mrs Joyce had told her interrogators she went to Germany because she was "morally unable to assist in Britain's war effort".

It is not clear to what extent she may have aided the enemy

Captain Skardon

Captain Skardon was apparently happy to accept she had followed her husband to Germany out of loyalty.

"In her political beliefs she merely echoes the views of her husband," he wrote.

"It is not clear to what extent she may have aided the enemy; but she was a persistent speaker and writer for German radio ... her case is only less serious than that of William Joyce because she was less well-known and not so frequently heard in England as her husband."

Mrs Joyce was deported to Germany that year and interned as a security risk, but later returned to Britain and died in London in 1972.