Key Points:

Tina Brown edited two of the world's most famous magazines, the New Yorker and Vanity Fair, and became the toast of Manhattan before launching Talk, her own ill-fated title, as the last century drew to a close. But now Brown, the Briton who conquered New York, is back, touting an explosive new book about Princess Diana to mark the 10th anniversary of her death. And she is not pulling any punches.

In The Diana Chronicles, Brown portrays the Queen of Hearts as a "spiteful, manipulative, media-savvy neurotic" who was planning to move to America and was looking for a billionaire husband in the months before she died.

It begins with a colourful account of Brown's last meeting with Diana, over lunch at New York's Four Seasons restaurant a decade ago at which the Princess wore a green Chanel suit and 20cm heels, and gossiped conspiratorially about her love life.

The fact that Brown opens her book by recounting an intimate lunch with its subject will delight her admirers and irritate her critics, who claim her reputation as a magazine genius rests on her ability to charm her way into the right circles.

The book, for which she is thought to have received a £1 million ($2.7 million) advance, will be published by HarperCollins, which was once run by her husband, former British Sunday Times editor Sir Harold Evans, 79, and serialised by Vanity Fair, the magazine she used to edit. Much is riding on its success.

Although Brown has remained in the public eye, writing a regular column in the Washington Post, she has had a quiet few years by her own frenetic standards.

One high-powered magazine editor quips: "She has been a bit like a minister without portfolio for a while."

Brown was forced to reinvent herself after the collapse of Talk, the glossy monthly she hoped would become the cornerstone of a modern-day media empire. The title's 1999 launch party on Liberty Island is remembered by Manhattanites as one of the most opulent ever thrown; Brown holding court beneath the Statue of Liberty.

But she would later confess that Talk couldn't live up to its own hype.

"We gave an insanely huge launch party that really subscribed to the great David Brown [film producer] theory of show business - which is never give a party that's better than the movie."

Many in the bitchy media world enjoyed watching Brown endure the first setback of a glittering career that had begun in London nearly 25 years earlier. She was expelled from three boarding schools for minor misdemeanours, went to Oxford University, and moved to London shortly after graduating in 1974. By then, Brown had established a reputation as a talented writer, winning the Sunday Times drama award for her one-act play Under the Bamboo Tree, and had embarked on a series of romantic liaisons with high-profile writers including Auberon Waugh and, later, Martin Amis.

But she would make her name as an editor rather than an author after being handed control of the ailing society magazine Tatler in 1979 at the age of 25, using her literary contacts to improve content and boost circulation. The title was acquired by Vogue owner Conde Nast four years later. "Si" Newhouse, its charismatic and powerful boss, would become Brown's patron and mentor.

Within a year of the Conde Nast acquisition Brown resigned from Tatler and moved to New York as an editorial adviser on another of the group's titles, Vanity Fair, becoming editor-in-chief in 1984.

Once again, circulation soared as Brown, with Conde Nast's millions, turned the title into a must-read, creating a potent editorial mix by hiring big-name writers including novelist William Styron, and photographers such as Helmut Newton. In 1991, she persuaded Demi Moore to pose on the magazine's cover naked while seven months' pregnant. But long before that, in 1985, Brown caused a stir of a different kind by writing a highly critical article about Diana under the cover-line, The Mouse that Roared, which claimed her marriage to Prince Charles was already damaged beyond repair.

It was vintage Brown, drawing on well-placed contacts to write an agenda-setting piece that punctured the myth of the couple's fairy-tale marriage.

Sources close to Brown claim she has repeated the trick more than two decades later, speaking to more than 200 contacts, including Tony Blair, as she researched The Diana Chronicles.

Many of those relationships were forged in the 1990s, after Brown took over the New Yorker, an appointment that elevated her, along with her husband, to the pinnacle of Manhattan society. She had met Harold Evans in London years earlier, and married him at the East Hampton home of Ben Bradlee, famed Washington Post editor, in 1981.

Such was their influence during this period that the couple could dispense with their surnames and still excite instant recognition, perhaps the ultimate accolade the celebrity era can bestow.

At their opulent home close to Central Park, they entertained lavishly.

Evans was appointed president of Random House publishing, which was then part of the Newhouse empire, in 1990, further strengthening their relationship with the family.

It was often difficult to discern where the couple's professional existence ended and their personal lives began. Brown had famously said, on arriving in New York: "You don't make friends, you make contacts."

A workaholic, she reputedly faxed changes to articles from the gym and gynaecologist's and became a cult figure to some, epitomising the go-getting spirit of the City, but simply "a caricature" for others.

During her tenure at the New Yorker, from 1992 to 1998 Brown increased sales yet again, as she set about modernising the title by including photos for the first time and running shorter articles. Some members of the literary establishment did not like it, but it was a critical and commercial success. According to Michael Wolff, America's pre-eminent media commentator: "The New Yorker was a much more interesting magazine under Tina's hand."

Brown watched with frustration as Conde Nast made huge sums, selling the rights to more than 20 New Yorker articles she had commissioned to film studios and publishers. She approached Newhouse with a plan to branch out into books and films, asking for a stake in the company. Newhouse refused; Brown resigned.

According to Toby Young, the British journalist who was a contributing editor at Vanity Fair under Brown's successor, Graydon Carter: "Tina only ever made one mistake. She decided that editing one of the most prestigious magazines in the world wasn't enough for her. Being an employee wasn't enough, she wanted to be a media mogul."

Rebuffed by Newhouse, she teamed up with Harvey Weinstein, the boss of Miramax film studios. Employing the language of the last dotcom boom, Brown and Weinstein talked about "synergies" and "cross-pollination", arguing that the actors who starred in Miramax films would grace the cover of Talk, and creating a publishing arm to sell books inspired by its articles.

It was an ambitious scheme, but it didn't work. The company lost money and Weinstein was unwilling to sustain the losses. He called time on the venture in January 2002. It is testament to Brown's resilience that she walked away from the wreckage of Talk with her dignity and her reputation, intact, if diminished.

One of her most vociferous critics describes her as "toxic waste", but Brown remains sanguine in the face of such schadenfreude.

"It was completely understandable. Talk became this kind of hysterically over-inflated sort of media story. And it was fun for people to write about. I thought that it was a little excessive at times. But I'm kind of used to that at this point."

A kinder critic says: "She weathered this terrible storm of personal publicity and she's okay. She's a reputable person in New York. But after Talk her career had no second act."

Perhaps not yet, but even Brown's enemies predict The Diana Chronicles will be a bestseller, and concede she has chosen her subject wisely.

- Observer

The Brown Lowdown
Born: Christina Hambley Brown, November 21, 1953, Maidenhead, England, to George, a film producer, and his agent wife, Bettina.

Married Harold Evans in 1981, with whom she has two children, George and Isobel.

Best of times: The 1999 launch party for Talk magazine, held in the shadow of the Statue of Liberty and attended by New York's social elite, which confirmed its host's status as the city's power-broker in chief.

Worst of times: Talk's dramatic collapse in 2002 and the subsequent split from business partner Harvey Weinstein. Brown spent months wrangling over a settlement.

What she says: "Will a racy cover line encourage a reader to read a serious and challenging 10,000-word piece? If it does, hooray. That's what it's about. Marketing. I won't be satisfied with an issue until everything has been done to make it more exciting and more appealing. I'm completely obsessed with the need to seduce readers all the time. I feel that we're in a fight. A war."

What others say: "A tyrant. Joseph Stalin in high heels with blonde hair from England" - American novelist Jamaica Kincaid.

Tunnel vision

Diana, Princess of Wales continues to exercise her power to stir controversy 10 years after her death.

British television's Channel 4 is having to defend its plan to broadcast a documentary featuring a controversial photograph of the Princess in the aftermath of the tunnel car crash in which she died.

Friends of the Princess were said to be "furious" at the decision to broadcast the documentary, which is reported to include a picture of Diana receiving oxygen from a French doctor.

The programme Diana: The Witnesses In The Tunnel is due to be broadcast on June 6.

Channel 4 says: "There is genuine public interest in exactly how events unfolded in the hour or so immediately after the crash. C4 has carefully and sensitively selected the pictures used in the programme. These photographs are an important and accurate eyewitness record of how events unfolded after the crash.

"Some photographs will be of the scene inside the tunnel but in none of the pictures is it possible to identify Diana or indeed any of the crash victims."

Rosa Monckton, whose daughter is the late Princess' godchild, is quoted in The Times saying: "She is not here to defend herself. She can't be hurt by it, but her boys can. Above all else, Diana was a mother."