Diana groupies maintain their vigil

Where's John?" asks Susan, a smartly dressed elderly woman, as she joins the small group waiting for seats in the public gallery at the inquest into the death of Diana, Princess of Wales.

John, with 'Diana' written on his forehead and 'Dodi' across his cheeks in blue face paint, has been at the front of this queue every day since the inquest started four months ago, having given up his job as a chef at a golf club to attend.

Middle-aged with an anxious, high-pitched voice, he rises at five every morning, leaving his home in Enfield, north London in time to arrive outside the Royal Courts of Justice by 7am. On the first three days of the hearing, he slept outside the court to make sure he got in.

These days he doesn't need to bother. There have been spare seats in the roped-off public area of the High Court almost every day and the overflow marquee, with space for 100 more spectators, is often empty.

Paul Burrell, who has drawn the biggest crowd so far, only half-filled the extra tent. But John hasn't allowed himself any lie-ins: "I don't want this to be handed me on a plate. I am doing it for Diana. I want to know the truth," he says.

John soon rejoins the group of half-a-dozen Diana obsessives who are enthusiastically dissecting the previous day's evidence while waiting to take up their habitual seats in court. Susan spent the evening doing background research, such as phoning the Ritz to find out the alcohol content of the two glasses of Pastis allegedly drunk by chauffeur Henri Paul immediately before the crash.

Others have been re-reading court transcripts online, and have brought bags full of notebooks, newspaper cuttings and packed lunches. Lee-Jon, a scruffy middle-aged man who smells faintly unwashed, insists on taking my photo before chatting with me.

"I photograph everyone I meet," he says. "I might need to remember them." He is researching a "fact-stroke-fiction" novel about the Princess of Wales's death, and calls the group the 'Diana Centurions'. "We're the guardians of her memory", he says.

They are a motley force. Far-fetched conspiracy theories abound. One woman, Susan whispers to me, believes MI6 are trying to kill her. And none can understand why their numbers are so sparse.

"More people come when they expect something salacious", says Susan. "But usually it's only us." By comparison, queues to sit in on the 2003 Hutton Inquiry formed at dawn, and latecomers were often unable to get a seat even in the overspill rooms.

But this group of eccentrics has one very powerful member: Mohamed Fayed, whose wealth has turned what could have been a formality into a marathon set to last at least three more months.

The Harrods owner, who attends almost every day with his six bodyguards, not only fought and won a legal battle to see the inquest conducted in front of a jury rather than in private, and hired crack QC Michael Mansfield to push his thesis that the couple were murdered by the British security services at the command of the Duke of Edinburgh, but is also paying many of the lawyers here.

As owner of the Paris Ritz, he is funding the hotel's legal team, and he is likely to be contributing to the cost of the QCs employed by the family of Henri Paul.

So far, the inquest has added little but juicy nuggets about Diana's private life to what was already concluded at the 2001 French inquest and the British police inquiry led by Lord Stevens - that the pair died because they were being driven too fast by a drunk driver.

But the hearing, which has already called some 150 witnesses and is set to cost the taxpayer at least £10m, seems unlikely to quiet the concerns of Fayed and his tiny band of fellow conspiracy theorists who have made themselves at home in the courtroom. ·