On another occasion Mr Smith claims he was beaten up in a street near his home by the same man. Within days, police set up a covert CCTV surveillance operation and installed panic buttons in his home, but no evidence of the gunman was ever found. A subsequent report by Sir Michael Peat, Prince Charles's private secretary, mentions that Ms Shackleton, a cousin of The Sunday Telegraph's editor, Dominic Lawson, described Mr Smith's claims as "very serious" and meriting a thorough inquiry. At the same time, the Palace began an internal investigation into Mr Smith's claims. It was carried out by Fiona Shackleton, then the Prince's principal lawyer, at his request. In an interview in today's Mail on Sunday, Mr Smith claims that after Diana made it known she had recorded his allegations of rape he was threatened by a hooded gunman who told him: "Keep your mouth shut or that will be it." Mr Smith said that a campaign of intimidation began in autumn 1996 when he opened the front door of his home in Twickenham, Middlesex, to find a man pointing a 9mm Browning automatic pistol at his head.

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She was feeling battered by the Palace, with its propaganda machine suggesting she was unstable Her fear was that this was being done to take her sons away. According to Mr Smith, despite knowing about his problems with alcohol, the Princess was keen to ply him with champagne when he went to the Palace. He told Diana about the assaults, and he claims that her response was: "You will get over this ­ I have been through worse." Months later, Mr Smith was back at the Priory receiving treatment for alcohol abuse. However, it is not clear how much detail he went into about the incidents.Soon after, Mr Smith had a nervous breakdown and was treated at the Priory Clinic at Palace expense. Mr Smith said that he spoke to medical staff at the clinic about how disturbed he has been by his experiences in the Falklands war, but did not mention the alleged sexual assaults.Then, Diana intervened in this story with consequences that are beginning to prove devastating for the Royal Family.

The Princess had apparently heard the whispers going around Kensington Palace following Mr Smith's talk with Ms Burgess. She visited the valet at the Priory and asked him to call on her at Kensington Palace to discuss his troubles. He mentioned what had happened, for the first time, to Elizabeth Burgess, an assistant personnel officer at St James's Palace. The attack, Mr Smith said, left him deeply traumatised, and his health began to deteriorate. That same year, Mr Smith's marriage collapsed and his wife left him for another man. The combination of all his problems, he said, left him unable to cope with work.