This is one rose that will never be allowed to wither. For this particular flower - always a nice little earner - has blossomed into a booming industry, too lucrative to be left to rest in peace of dignity. A glimpse behind the petals reveals a sticky, crawling mass, feeding off the glamour and pathos of a young mother who died before her time.

This week, the Diana industry got a fresh dose of fertiliser in the form of "the most searching journalistic investigation yet" into her death. The Times of London ran extracts over five days and readers were disposed to expect authoritative research; the authors - Thomas Sancton and Scott McLeod - are senior journalists with Time magazine. The fact that the extracts repeat a mass of unproven, unsourced information laced with hilarious conspiracy theories was lost in the type.

Take one example. Mohamed Al-Fayed and "persons close to him" were important sources for the authors. Thus they report his movements at the Paris hospital: "Al Fayed decided to go first to the hospital to see the Princess. Upon arriving at Pitie-Salpetriere, he was met by. . . Philippe Massoni, the police chief, who told him that she had just died. Al Fayed was taken to see the body. `I was in shock', he later told associates. `I saw her and I prayed. She looked beautiful, peaceful and serene'."

And this is how the Mirror - in an "exclusive" interview this week with Al Fayed - reports the same incident. "Mr Al Fayed shudders at the memory as he says: `Diana was already in the mortuary and I had the opportunity to go and see her body. But I said no. It was just too shocking for me to go and see her. The thought of this beautiful, serene princess who I loved so much lying dead would have been too awful. Instead I went to see Dodi's body."

Who to believe? Does it matter?

Then there is the conspiracy theory - that Diana and Dodi were murdered by the British Establishment. The full page of speculation about a possible preg nancy - which, say the authors, "under normal circumstances would have been purely a private matter" - used to introduce the extracts in the Times, was legitimate, they claim, "because if a pregnancy were confirmed, the conspiracy theories would be uncontainable".

Yet there's not a shred of credible evidence that the princess was pregnant. Take away the pregnancy factor and the authors concede there is no "convincing evidence" that Diana marrying a Moslem "would in itself have posed a direct, mortal threat to Britain's monarchy, political system or way of life".

But that doesn't stop them swirling away into a fantasy as convoluted as any romantic thriller, wherein a canny William might have converted to Islam after he became king - "or did so secretly beforehand and announced the adoption of his new faith after ascending the throne. If William then wished to remain king, it could have precipitated a full-blown constitutional crisis".

Yes, and if my aunt had - um - male genitalia, she'd be my uncle.

On such myths and hypotheses has the Diana industry been sustained. Her brother, a member of the same Establishment, has shown more pragmatism, reaching

instead for the tangible dividend of a Diana theme park.

Earl Spencer has sold 126,200 tickets dressed up as smart invitations to the family home at Althorp. For £9.50 (discounts for pensioners etc.), these suggest that his "guests" will find him "At Home" on a specified day between July 1st and August 30th.

They shouldn't count on it. But what the guests should get is a tour of the house, a gawp at the dead sister's best frocks in the newly converted stables, and a gape across the water at her last resting place.

Estimates of the two months' revenue range from £760,000 and £1.4 million. The concession that any profits above the cost of revamping Althorp will go to Diana's memorial fund (though the Earl has no plans to open his accounts to the public) hasn't quelled some public distaste.

In the words of Roy Hattersley, what Lord Spencer is proposing is to sell the memory of the Princess of Wales: "There are some things for which tickets should not be sold. And the grave of a young woman who died in a car crash is one of them."

Lawyer Anthony Julius may have lost a valued client (he won Diana her generous divorce settlement) but he's not letting it cloud his commercial judgment. As chairman of the Board of trustees of the Diana Memorial Fund - beneficiaries to be the sick, the disabled, the forgotten, the disadvantaged - which legal firm did he choose for legal services to the fund? His own, Mishcon de Reya.

And of all who charged nothing for their services to the fund, who bucked the charity trend? Right. Mishcon de Reya, sending a bill for half a million pounds (around £250 an hour) for two months work.

And so the circus continues, albeit at a less exalted level. Only this week, an Englishwoman of dubious credibility got huge media coverage for alleging that Dodi Fayed had fathered her child.

Diana books, videos and partcollections still sell by the million. Andrew Morton's book remains in the top 10 UK hardbacks and at least one Hollywood movie is in the making. In the urgent hunt for live substitutes, the hapless Cherie Blair is trotted across double page spreads and her dress sense dissected.

Meanwhile, in academic circles, they've discovered a fashionable new subject: Diana studies. The girl who left school without an Olevel to her name and was considered a bit of an airhead in life, is now the subject of entire conferences across the world.

Dianaology has featured heavily in such publications as the British Medical Journal, the New Left Review and the literary magazine, Granta.

Last week, specialists in art history, feminism, sociology, history, psychology, media and religious studies all threw their penny's worth into a University of Kent conference entitled "New Sensibilities", picking apart the public reaction to Diana's death.

But Berlin was first off the blocks with the Free University's series of 13 lectures on the princess. Was Diana a "living simulacrum" or a symbol of "faux modernity"? What does the reaction to her death tell us about "uncertainty and social psychological responses"? Could that reaction be described as "grief-lite"?

Expect such questions on examination papers near you soon, in what is now known as the "post-Diana era". As for the ordinary middle-Englander, the question is, was the "grief" really as "lite" and transitory as many observers predicted? Nearly six months later, the answer appears to be no.

A straw poll among half a dozen English people of reasonable intellect this week revealed that two had played music from Diana's tribute album on Christmas Day - and wept. The other four are still "saddened" - but not to a disabling degree.