In life she was a visitor, writes John Carlin. Now the US wants posthumous possession of her
"She was America's princess as much as she was Britain's princess."

If these had been the words of a bereft Maryland matron leaving a bouquet outside the British Embassy in Washington, or a condolence note on the Internet from a 12-year-old in Detroit, one's reaction, as a British subject, might be an indulgent, mildly patronising smile.

But coming as they did from a hard-nosed newsman, the foreign editor of the gritty Chicago Tribune, one could be tempted to conclude, unforgivingly, that the poor chap had become so caught up in the week's journalistic frenzy that he had lost his mind. What was he thinking?

The truth is that he was not far off the mark. For Americans have indeed taken posthumous possession of the People's Princess. The media, providers of the public forum where Americans forge their sense of collective identity, would not have delivered scrutiny more intense had it been Hillary Clinton who died last weekend.

Yesterday all the national networks began their live coverage of the funeral long before dawn and saw through the event - "out of respect" - without commercial breaks. On Monday ABC, CBS and NBC broadcast the prime time news live from London, all dedicating their entire programmes to coverage of Diana's death. The rest of the week, in response to insatiable popular demand, they bombarded American screens with one-hour "specials" and round-the-clock discussions where every pundit - from OJ Simpson's defence lawyer, Johnnie Cochran, to Nancy Reagan, to Michael Fox - anatomised the consequences of the tragedy with as much earnestness, intimate knowledge and passionate concern as the BBC has been able to muster.

From the west coast to the east the American newspapers have dedicated miles of column inches to the story. On Tuesday USA Today published a special eight-page Diana supplement which, among other things, anticipated the popular press in Britain by crowning Prince William "a global teen idol". The New York Post wondered whether Elizabeth Hurley would play Diana in the made-for-TV movie. Staff columnists of the venerable New York Times, which ran a "Death of a Princess" section every day last week, each weighed in with their opinions. And on Thursday the paper's editorial claimed that the overwhelming media coverage suggested "a world out of whack" - an impudent and unwary observation given that the adjoining three columns were packed with letters from readers united in regret at Diana's demise.

Those who could not find space in the newspapers' letters pages vented their sorrow through that anarchically pure democratic medium, the Internet. Diana's death has launched a thousand websites, most of them venues for the grief-stricken, some of them forums for novel variations on that all- American pastime - the conspiracy theory. Have Di and Dodi done an Elvis and faked their deaths? Did the Queen kill her? Or was it the Israelis, the CIA? All perfectly insane questions posed by, in some cases, seemingly sane people. What is interesting about them in this case is that never before have America's kooks ventured speculation so wild on an incident that has taken place outside their country's boundaries.

Another symptom of how deeply Americans have internalised Diana's death and appropriated her memory is the outrage they have voiced at the paparazzi and the tabloid press in general. Safeway and Giant, the country's two biggest supermarket chains, pulled two tabloid weeklies from their shelves because they carried the pictures of Di and Dodi canoodling on a yacht. Several smaller outlets have taken the principled stand of banning all the tabloid papers. And a posse of Hollywood stars - among them Tom Cruise, George Clooney and Sylvester Stallone - have jumped at the chance to vent their long-accumulated rage at the paparazzi's intrusiveness, imploring the government to introduce tighter privacy laws and the public to stop buying the tabloid scandal sheets.

In everyday conversation ordinary Americans of all races, from all walks of life, have professed themselves devastated by the news of Diana's death. At a barbecue last Monday in Washington, where all but one of the 20 guests were black, the conversation dwelt on little else. A lady who was 78, and had endured enough grief in her own life for one reasonably to expect she might have none to spare for a complete stranger, said she was terribly upset. "It feels almost like a loss in the family. She was so kind and so beautiful, and yet she had such an unhappy life," the old lady said.

In response to sorrow so generalised, Washington's politicians have responded in unprecedented fashion. The Senate, ever alert to the voters' mood, sought to declare yesterday a "day of national mourning" in honour of Diana's funeral, but were prevented from doing so by the discovery that this was a right constitutionally reserved for the President. So instead the Senate voted unanimously to call for a "day of recognition" of Diana's humanitarian works, a gesture reciprocated by the House of Representatives. Also, following the funeral service at Westminster Abbey, a memorial service was held at Washington's National Cathedral.

What is going on? How has it come about that a nation whose schoolchildren are taught in history class to scorn the "tyranny" of the English monarchy have suddenly emerged as pretenders to the jewel in the British throne? Why is it that numerous American commentators have sought to expand into truth the rumour that Diana planned to move to the USA.

Part of the answer lies in America's status as the celebrity culture par excellence. Americans worship the likes of Madonna and Harrison Ford like the Pope worships the Virgin Mary. It is from celebrities that many derive their sense of nationhood. (I love Sylvester Stallone therefore I am American.) Their presidents must be celebrities, otherwise they would not be elected. Norman Mailer made the point after the last election that Bill Clinton won because he projected the image of a Hollywood star, while Bob Dole lost because he came across as a supporting actor.

What seems to have happened is that the inhabitants of the nation that gave us Marilyn Monroe and Elvis Presley find it hard, if not impossible, to reconcile themselves to the notion that the world's biggest, classiest contemporary celebrity by far (who comes second, Michael Jackson?) should have come from another country. But that, many seem to be saying to themselves, is merely an accident of birth. Because in many ways, and perhaps they have a point here, she was so American.

Her New Age predilections - the astrologers, the psychics, the aromatherapy - were more Nancy Reagan than House of Windsor. Her dieting, her visits to the gym were lifestyle options patented in the USA. No less typically, candidly American was her celebrated TV confession and her (purportedly unauthorised) tell-all book. She did a Jackie Kennedy and auctioned her dresses not in London or Paris but New York. She visited America frequently and felt right at home, revelling in the lavish attentions of the opulent and famous and delighting in the effusive responsiveness of the public to her charms. For she seemed to have adapted brilliantly another American invention - image manipulation, which all aspirants to political office in the USA struggle to learn but which she appeared to have absorbed and refined naturally.

She was, in short, a thoroughly modern woman and, like it or not, most of what modern is originates in the States.

But many Americans feel she also had more enduring qualities. Many view her as the incarnation of their country's dominant myth. Take this from Tuesday's Miami Herald. "She was an American dream, a superstar Cinderella with the polish of a natural-born socialite ... In a way she fulfilled the American dream. To emerge from obscurity and overcome adversity and make something of herself."

Elaine Showalter, a student of American popular culture who teaches English at Princeton University, noted the difference between the stuffiness of Prince Charles and Diana's "very American sensibility". "We have a sense here in America that anything is possible, that you are not a predetermined person; that if you are a woman from whom nothing is expected but you want to make your life count, you can do it. She shared that spirit and that's why she appealed so much to Americans."

More crassly, but perhaps no less significantly, she also appealed to Americans and people everywhere as the star of the world's longest-running, best-known soap opera. Diana, the prime flesh and blood manifestation of the phenomenon of globalisation, provided an invaluable social service to the planet. She gave us all something to talk about. If you were sitting at an airport bar in Dallas, Buenos Aires or Bangkok and wished to strike up a conversation with a complete stranger, no opening gambit was more likely to establish common ground or elicit an opinionated response, than a question about Princess Diana. The same holds true, only more so, now that she is in the grave.

John Lennon, her martyr forebear, once ventured the heresy that the Beatles were bigger than Jesus. In Britain today that might be true of Diana. In America it would be an exaggeration. But she comes close.