A princess, her lover and the lost ring that led to the butler

Diana's sister asked police to question the former royal butler about the fate of the princess's box of private possessions

The call came to Scotland Yard's special inquiries unit on 20 November, 2000. On the phone was Lady Sarah McCorquodale, the sister of Diana, Princess of Wales, with a delicate matter, a missing memento of an affair between the mother of the heir to the throne and an indiscreet cavalry major.

The object was a signet ring belonging to James Hewitt, the caddish former lover of the Princess. She had retained it, as one of her most private possessions, in a wooden box that disappeared from Kensington Palace after her death.

Now, it seems, Lady Sarah, one of the executors of her sister's will, wanted to know where the box was and said detectives should ask Paul Burrell, Diana's butler and confidant.

Some eight weeks later, officers from the Metropolitan Police obliged those behind this high-level lost-property inquiry by arriving at Mr Burrell's home in Cheshire at 6.50am and conducting a search which took 12 hours and allegedly uncovered a huge cache of royal memorabilia belonging to his former employer.

Yesterday, Court One of the Old Bailey, where the 44-year-old former butler is standing trial for allegedly looting the Princess's London apartment, heard claims that the visit by four detectives had, at least in part, been a private mission to save royal blushes. That mission was to retrieve an item whose existence had been so closely guarded a secret that not even the jury trying Mr Burrell was initially allowed to hear about it.

As a result of a request by the media, the trial judge, Mrs Justice Rafferty, gave permission for the existence of the ring to be confirmed in open court, and for its cameo role in the fog of allegation and counter-allegation surrounding a royal manservant to be revealed.

The jury of seven men and five women heard that as well as the ring, the missing box had contained private letters from the Duke of Edinburgh to Diana, an audio cassette with a voice recording by an unnamed individual and other items of jewellery.

Neither the box nor any of the other items it contained were found at Mr Burrell's home, the court was told. Instead, the Scotland Yard officers uncovered nearly 300 other royal possessions, ranging from intimate letters to her Abba records, allegedly taken from the Princess, with a further 25 valuables allegedly pilfered from the Prince of Wales and Prince William.

But the court's attention focused on the signet ring, and its implications for the significance the Princess attached to the five-year affair she started with the Guards officer in 1986 and was later revealed by him in a kiss-and-tell book.

The unspoken question was why, despite the betrayal of her lover, Diana had held on to the memento until her death in a Paris underpass five years ago and why her family was now desperate to get it back?

Lord Carlile QC, for Mr Burrell, put it to Detective Sergeant Roger Milburn, one of two officers in charge of the search of the former butler's Georgian house in Farndon, that the jewellery had been high on the police list of priorities when they arrived on 18 January, 2001.

Lord Carlile said: "It is right that among the items you hoped to find were James Hewitt's signet ring ... and that signet ring was regarded as being potentially very significant and important." Indeed, such was the significance of the ring and the other contents of the box that the police officer had offered to halt the team's inquiries at the house if they were returned to Lady Sarah and Frances Shand Kydd, Diana's mother, it was claimed.

Lord Carlile told DS Milburn: "You said to [Mr Burrell] that Lady Sarah had asked you to retrieve a box of personal documents and that if the box was produced that you would not go on and search the house."

He added: "You had your head turned by the involvement of Lady McCorquodale and Lady Shand Kidd and this coloured what happened when you went to search this home."

The detective, in his second day of cross-examination, strongly denied the claims, saying police had visited the Burrell home on a different line of inquiry. The questions about the box had been no more than a polite inquiry for Lady McCorquodale, the court heard.

DS Milburn said: "She simply wanted to ask him if he knew the whereabouts of some documents [in the box]. We had no allegations from Lady McCorquodale that warranted Mr Burrell being arrested on suspicion of theft of these items."

The exchange of claims of cloak-and-dagger behaviour on the third day of the trial came as the defence took another eyebrow-raising step in its attempts to claim police bungled their visit to Church View, the three-storey house Mr Burrell shares with his wife, Maria, and their two sons.

Shortly before midday, the jury was treated to a video tour of the property shot last weekend on a home camcorder by the defendant, who denies three charges of theft.

The tape, a sort of judicial version of the television programme Through the Keyhole in which contestants guess the identity of a celebrity by the contents of his or her home, duly took Court One through rooms dotted with photographs and possessions betraying an all-too- obvious link to the Royal Family.

The purpose was to ask why the police had not made their own film while they emptied the contents of Mr Burrell's loft, bedroom wardrobe, study bookshelf and other receptacles. The more subtle subtext was also to give visual proof of what Lord Carlile said was his client's role as "very properly, an extremely close friend" to the Princess.

The video panned past framed royal memorabilia, a San Francisco 49ers cap and a signed record, and on to informal pictures in the upstairs dining room and lounge of the Princess with Mr Burrell, the Princess with his two sons at Alton Towers adventure park, and signed pictures from Prince Charles and Fergie.

Almost as if he'd been asked the TV show's catchphrase "Who Lives In a House Like This?", Lord Carlile said: "Is it not obvious that this is a house lived in by someone with a connection to the Royal Family, or someone who is a royal nut, or possibly both?"

A rapid tour of the bedrooms, bathrooms, and even the suitably untidy sleeping quarters of two teenagers also revealed gifts including a watercolour by Prince Charles and a sculpture of a kingfisher given to Charles and Diana as a wedding present by President Ronald Reagan and his wife Nancy.

When asked about the sculpture's origin, DS Milburn said: "Had I known that, I probably would have taken it."

The detective said he accepted, with hindsight, that the police search should have been recorded but added that his team had not expected to find so many items and were trying to be discreet by not calling in a uniformed video team.

DS Milburn said: "This was not a murder scene; it did not require forensic examination."

The case continues.