The unsolved riddle at the heart of Max Mosley’s orgy trial is what he said to his S&M madam in a string of e-mails that remain missing.

Messages between the pair have been deleted. The News of the World suspected that they contained plans for a Nazi concentration camp theme to the party in his basement flat.

The judge ruled that he could find no evidence that the party was intended to be “an enactment of Nazi behaviour”, nor any “genuine basis for the suggestion that the participants mocked the victims of the Holocaust”.

Mr Mosley and the madam, known as Woman A, strongly denied any such suggestion, but she refused permission for her internet provider to release any copies of the correspondence. The judge concluded that he would have to accept that “it is not possible to come to a definite conclusion as to precisely who, or why, the claimant’s e-mail traffic was deleted”.

The 68-year-old motor racing chief made a habit of recording his spanking sessions so he could relive them later. He had to disclose these discs to the newspaper for the trial.

At a party on March 8, where Mr Mosley and a German dominatrix were beating women posing as prisoners, Woman A can be heard clearly saying: “But we are the Aryan race, blondes.” Thwacking noises and moans of pain follow on an audio recording played in the High Court.

Challenged about this in the witness box, she said she was unaware of the meaning of Aryan, had no interest in history or politics and was unable to explain why she used the words.

Mr Mosley and Woman A e-mailed each other between that party and the orgy on March 28, which was filmed secretly by the News of the World.

On the day that the newspaper exposé appeared, March 30, Woman A deleted the e-mails from her desktop computer. She said she did so “in a state of shock and panic” in the hours after learning of publication. She denied that Mr Mosley suggested erasing the messages, although he did ring her that day. “The e-mails would actually prove that there was never, ever, ever any Nazi references,” she said.

A laptop, kept at Mr Mosley’s flat in Chelsea, West London, where his orgies took place, was surrendered to computer experts but the e-mails had been deleted from it as well.

Another participant, Woman E, was asked to consent to Microsoft searching its Hotmail system for the missing messages so they could be disclosed for the trial. She refused, saying she feared that other private matters would fall into the hands of the newspaper’s lawyers.

Mr Mosley said he deleted the e-mails because his computer was slowing down. He had been warned by Bernie Ecclestone, the Formula One chief, and Lord Stevens of Kirkwhelpington, former head of the Metropolitan Police, that he was under surveillance, and he feared that the computer was infected with spyware. “It’s a great pity we haven’t got them,” Mr Mosley said under cross-examination. “No one wants those e-mails more than I do because it would stop this discussion.”

Some e-mails between Mr Mosley and the madam have been recovered. They show that Woman A had devised a new scenario for the March 28 party which was to include German interrogation, a nasty new prison guard and punishment rape scenes.

The News of the World suffered from a gap in its evidence too. Its star witness should have been Woman E, the dominatrix who smuggled a camera into the orgy and made a film of Mr Mosley’s S&M antics. She was the only participant who, the newspaper hoped, would confirm it was a Nazi party, a suggestion strongly denied by Mr Mosley and the four other Miss Whiplashes who testified. Under cross-examination, Neville Thurlbeck, the chief reporter who broke the story, denied a suggestion that he had threatened to expose his source’s identity in a follow-up article. “If I had threatened Woman E in the fashion you suggest, she wouldn’t be coming to court for us tomorrow, I’m pretty sure of that,” he told James Price, QC, Mr Mosley’s counsel.

The newspaper had originally promised her £25,000 if the story was the front-page lead but the Editor, Colin Myler, reduced the fee to £12,000, blaming the credit crunch. Mr Justice Eady was informed by the newspaper’s lawyers that Woman E would, after all, be unavailable because of her emotional and mental state.

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