The M15 documents released by the Public Records Office call into question the widely-held image of Wodehouse as a vain but harmless fool.

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The author had been interned in Berlin in 1941 after the Germans overran France, where he had been living in a villa in Le Touquet.

During his internment he infamously made broadcasts to England and the US, containing whimsical descriptions of the internment camp.

The broadcasts caused outrage back home, where some compared him with the notorious propagandist Lord Haw-Haw and thought he had damaged the war effort.

When interviewed by MI5 in September 1944, the author admitted he had made a "hideous mistake", but argued that his broadcasts were not pro-German.

"It never occurred to me that there could be anything harmful in such statements as; when in camp I read Shakespeare, that men who had no tobacco smoked tea and that there was an unpleasant smell at Loos prison," he said after the war.

'Reward for propaganda'

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MI5 agreed that the broadcasts were not pro-German and had been unlikely to assist the enemy, and decided against prosecution.

The author moved to the US in 1945 and lived there until his death in 1975, aged 93.

But a memo of a 1946 meeting between an M15 officer and the then Director of Public Prosecutions, Sir Theobald Mathew, reveals that his case was re-evaluated after the war.

"The Director said that he now takes the view that, if Wodehouse ever comes to this country, he should be prosecuted," the officer recorded.

"In view of the observations by Lord Justice Tucker that the motive which prompted the broadcast was immaterial, he thought that the authorities should now bring Wodehouse to trial and leave the jury to decide the question of his guilt or innocence."

Payments from Germany

Later, MI5 learned of documents found in the former German Embassy in Paris, which detailed suspicious payments made to Wodehouse and his wife Edith.

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One letter from the embassy requested that Wodehouse's French villa be well kept "in view of the propaganda value of his work".

The transactions were seen to "strongly suggest" that Wodehouse was working for the embassy.

But MI5 noted that the Germans may simply have been transferring the author's funds left behind in Berlin when he moved to France in 1943.

Outrage from fans

Suggestions of treachery have outraged fans of Wodehouse, who insist he had simply been naive.

Norman Murphy, chairman of the PG Wodehouse Society (UK), said there was nothing suspicious about a series of payments from the embassy to the Wodehouses.

"The so-called payments were probably either payments of his royalties or maintenance because the Germans didn't want their world famous prisoner to die in their hands," he said.

"His financial affairs during the war were such that his wife had to sell her jewellery, and they had to borrow money to eat.