He is probably the richest journalist in England, and he has certainly been one of the most reviled. But it didn't need to turn out like that. He would still be languishing quietly in Muswell Hill if Diana had not decided that he was her Noah.
We now know that Andrew Morton's Diana, Her True Story was based on the Princess's own words. He has the six C90 tapes to prove it, plus the hastily updated and snappily retitled Diana, Her True Story - In Her Own Words, which will earn him a second fortune for practically no extra work, the cheeky little monkey.
But the big question, I suppose, is why did she, a woman with the world at her feet, pick him, a former Daily Star hack, and not, say, me, who wasn't so busy in 1991 that I couldn't have fitted her in between Supermarket Sweep and This Morning, if pressed?
Pure luck, Andrew? Because you happened to be researching her biography at the time she was desperate to get her side of things across? No, he insists. It was not merely a right time, right place scenario. Not by a long chalk. He's an historian and author, primarily. A serious bloke. The man for the job. Her official biographer, if you like.
Indeed, Diana's nickname for him, he reveals, was always Noah. "Tell Noah to get the story out," she would say to her confidants.
The nickname, he explains, arose after he'd been described in an American publication as a "notable author and historian". The resulting acronym tickled the Princess, he says. Personally, I think it quite touching that she could think "author" begins with an "o". But, then, Naah would have been a disaster. "Andrew Morton? Naah ..." And that would have been it, wouldn't it?
But, as it was, "I had been writing on royals for 10 years. I knew the social landscape. I knew the system. And I knew, already, that the reality of her life did not match the image. Diana's friends and staff were dropping dark hints about her unhappiness, and she needed the truth to come out, needed to confess. It was like Dostoevsky's moths gathering around the flame."
Obviously, Andrew's not just a hack who happened to land the journalistic equivalent of a big lottery win. He knows his Russian novels. I'm impressed. I didn't even know Dostoevsky kept moths. Certainly, he wants you to know he's an erudite and learned thinker.
"The outpouring of grief that erupted with Diana's death was very Chaucerian and medieval, don't you think?"He mourns her passing greatly. "We'll be lucky to see anything on such a scale in our lifetimes again."
Anyway, he was totally rubbished when, in 1992, the book first came out. He was a "tabloid vulgarian from Leeds" who wrote "novelette purple", and had made it all up anyway. The bulimia. The suicide attempts. Charles's adultery. Pull the other one, it's got the Hitler diaries on it. Initially, no newspaper would touch it when it came to the serialisation rights. "Basically, I was called a liar," he says.
Yes, he would loved to have shouted out "actually, Diana was in on this", but he couldn't.
"She trusted me. It would have been a betrayal."
Did he find the flak hurtful? "I didn't bother reading a lot of it, it was such crap."
How did he keep his spirits up? "By knowing I was being true to myself." He is quite big when it comes to self-belief, I think. He even, it has been suggested, used to think the Princess was a little in love with him. True? "No, absolute rubbish," he cries. Did he ever fall a little in love with her? "No. My interest was in psychologically understanding her. What had her childhood done to her? Why did she throw herself down the stairs at Sandringham? Why was she bulimic?"
But is Andrew being true to himself - or to Diana, for that matter - with this new, updated version of the book, which includes 69 pages of her own, transcribed words? The Red Cross was not impressed. It refused to accept a donation from him. Bob Geldof was even less impressed. He called Andrew "a loathsome creep gorging on the memory of the woman who handed him his cheque".
What does Andrew make of such reactions?
"I just didn't understand it. By attacking me, they were attacking the Princess of Wales, who wanted the story written." But she never wanted to be identified as the source, did she? "I'd left the tapes in my will to Sussex University, to be used after my death. It would not have occurred to me to reveal them, had she not died.
"I first met Mike (Michael O'Mara, his publisher) the day after the funeral. He was already being criticised for not doing a reprint of the original book, which was selling out everywhere. We had a long discussion about the need to revise the book, but if we did, should we use the tapes? It was not a decision we took lightly. I could have just reissued the first book, then gone to a beach.
"But, in the end, we thought we should use them, because people had this great need for openness and honesty. Lord Spencer's funeral oration got applause, because he spoke from the hip, and everyone wanted that. We couldn't not do it."
He and Michael O'Mara have since donated pounds 300,000 between them to a charity other than the Red Cross, that also helps land-mine victims. The first book, which was translated into 29 languages and sold in 80 countries, is said to have made them pounds 5m each. The new one has topped the best-seller lists since the day it came out.
Andrew Morton is a huge man : 6ft 4in; huge shoulders; huge hands; huge neck; huge, square jaw; hugely handsome in a very Christopher-Reeve-meets- Clark-Kent-via-a-shopping-spree-in-C&A sort of way. He thinks it was his height, plus, of course, his intelligence, that first recommended him as the Daily Star's royal correspondent. "I could see over the crowds, and knew that Philip was spelt with one "l''.
We meet at a hotel, which is a shame, because I would like to have seen his house in Highgate, north London, which is worth pounds 1m, and very smart by all accounts. He won't have it, though. The trouble with inviting journalists in, he says, is that they "later go off and spend three paragraphs sneering at your furniture".
I am disappointed, I tell him, but can see he has a point. I can't even leave my own house without sneering over my furniture. You should see the carpet in the front room. A horrible thing with swirly patterns on, it is. Even I think less of myself whenever I see it.
He goes on to grumble a lot about journalism today. It's all adversarial, he complains, "It's like everyone wants to get in the ring with me and take a punch." He prefers, he says, the American style, "because you can just go on and tell a story. Where can you do that here? Newsnight? I don't think so. All you can do is go on to Richard and Judy and have an hysterical phone-in." I tell him that not all British journalists are bitter and twisted and jealous. (But, that said, your tie's horrid and you do write novelette purple. "Like a gust of wind across a field of corn, her moods fluctuated endlessly." Not, I think, a line nicked from Dostoevsky.)
Andrew Morton was born and brought up in Yorkshire. His father, Alec, ran a picture framing and art materials business in Dewsbury. He thinks a lot of the enmity he aroused had to do with class hatred. "If you are given pounds 100m just for being born, it's OK. But if you work hard and earn some money, then the British despise you."
A bright boy, he went to Leeds Grammar, then to Sussex university where he studied history and developed an interest in aristocracies and elites. "It always fascinated me that so few people could own so much of the world." His father would have liked him to have taken over the business - he was brought up, he says, in an atmosphere of "one day, son, all this Winsor & Newton ink will be yours" - but he'd always wanted to be a journalist. His mother, Katherine, "had twitching curtain syndrome. She always wanted to know what was going on. And so did I."
Before arriving at the Daily Star, he had done his stint on local newspapers and had married his teenage sweetheart, Lynne, whom he'd met on a caravanning holiday when 17. (They have two daughters, now 12 and 14). His first ever royal job was chasing Prince Andrew and Koo Stark to Mustique. "Great fun. Great fun." Then, via the News of the World and the Daily Mail, he went freelance to concentrate on books. Prior to Diana, Her True Story, he had written eight marginally successful but highly forgettable books with titles such as Inside Kensington Palace and Prince Andrew, The Playboy Prince - which, even he accepts, "must be one of the worst books ever".
He began researching his Diana book in the winter of 1990. Of course, he did not expect Diana to collaborate. But, even so, he asked Dr James Colthurst - a mutual friend - if he would ask her to consider answering some questions. Amazingly, she agreed. Why? Because, he thinks, "she wanted to get her retaliation in first." Retaliation against whom? "Charles, for going back to Camilla shortly after their marriage. Then Charles got his own back by doing the Dimbleby thing, which was actually promoted as the complete riposte to Morton's book. Then Diana retaliated by doing Panorama ..." He says that any accusations that he might have further wounded Princes William and Harry with his revelations are ludicrous. "Their parents had said it all in public already."
But how did he feel when the tapes - which were recorded by Dr Colthurst in Kensington Palace, unbeknown to any royal officials - started coming back, and he heard the absolute dynamite that was on them? Did he call out to his wife: "Lynne, Lynne. Come listen to this bit. `Couldn't sleep, didn't eat. Sick the whole time ... Charles said I was crying wolf ... threw myself downstairs ... he's had a bracelet made for Camilla Parker Bowles - so rage, rage rage'"? And then did he and Lynne dance jubilantly about their then quite small and poky flat in Muswell Hill, knowing that they had hit the jackpot and were on their way to something much smarter and more Highgate?
Not exactly, no, he says. "When I first heard the stuff I did think: `My God, this is going to create a firestorm.' But first I had to prove it all, had to get other people to support what she was saying, which was tricky, because everything was being done in secret." Weren't her good friends in on it too? "To this day, I don't know who was and who wasn't. I never asked." Eventually, The Sunday Times agreed to serialise it, but only after Andrew Neil, "to his credit", agreed to take a second look at it.
If, by some miracle, Diana were to walk into this room now, I ask him, what would you want to ask her? "Was it worth it?" he replies. Was what worth it? "All of it." And what do you imagine her reply would be? "I think she would say `yes'. I think her experiences made her what she became, and she was getting to like what she became."
No, he did not take advantage of her when she was at her most depressed. "She had already come though the darkest periods, and was referring back to them."
So what now, then, for Andrew Morton, if, considering what he probably has in the bank, he even needs a "what now"? He insists he does. "I don't want to become the Neil Armstrong of biography," he says. For the last three years, he's been working on the authorised biography of the Kenyan president Daniel Arap Moi, which is due out shortly. This, he doubtless hopes, will boost his credibility as an important chronicler of late- 20th-century figures.
And, maybe, when it comes down to it, Andrew did do something important. Certainly, he managed to expose our royals for the mad and greedy and dysfunctional lot they are. A cracking scoop, whichever way you look at it. Although I'm not sure it has anything to do with Chaucer or Dostoevsky or being a Noah, frankly.
Both Andrew Morton and Michael O'Mara are supporting the work of HMD International to clear mines in Angola. Anyone wishing to make donations to the charity, should contact it at: Studio 9, 27a Pembridge Villas, W11, 3EP (0171-229-7447).
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