Paul Burrell returned from a 400-mile dash across England to retrieve a letter from Princess Diana which he said revealed a final "secret", only to announce he had left it in America.

But the much vaunted "secret" - which he raised at her inquest yesterday and said he would take to his grave - turned out to be no secret at all, the coroner revealed.

On Monday Mr Burrell was ordered by the judge to "Hotfoot" it from London to his home in Farndon, Cheshire, to retrieve the documents including the key letter.

But he returned from the trip, having had just two hours sleep, to reveal that the letter was not there.

In a note to the coroner, Lord Justice Scott Baker, he disclosed what the "secret" had been.

But the coroner told him in front of a packed audience: "(There is) not in fact one secret but two secrets and you describe them to me in the letter.

"But having examined the matter it doesn't seem to me that they are secrets at all.

"Both pieces of information are fairly and squarely in the public domain in one way or another, one of them indeed appears in your book The Way We Were."

The lack of a final "secret" came as a huge anticlimax after Mr Burrell's eagerly-anticipated testimony had been expected to reveal yet more intimate details about the Princess.

He has already told the hearing at the High Court how the relationship sparked friction with Diana's mother Frances Shand Kydd after she branded Diana a "whore" for dating Muslim men.

Mr Burrell, 49, who has flown in from the US to give evidence, told the court how Diana had made inquiries about a marriage to Mr Khan.

He recounted how he had approached his local Carmelite priest Father Anthony Parsons in Kensington to ask about arranging a "private" wedding between a Christian and a Muslim.

He said Mr Khan had been introduced to Diana's sons, Princes William and Harry, and had become part of the "fixtures and fittings" at the Palace.

"She did ask me if it would be possible to arrange a private marriage between her and Mr Hasnat Khan so I thought the first person I should really consult would be my parish priest.

"The Princess said that this was her soulmate, this was the man she loved more than any other and it was a very deep spiritual relationship."

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