But generally speaking they are of the Madame Vasso type and I don't think it's proper to publish that kind of material."The Diana book radically changed the style and content of royal bestsellers. "I think I've tried to set a new standard in royal publishing," he says. He was the man behind Andrew Morton's Diana: Her True Story which in 1992 blew the whistle on Charles and Diana's marriage, hastening the announcement that they were to separate.The book was the stuff of publishers' dreams. In its first year, 4.5 million copies were sold world-wide, with translations in 23 languages.

In O'Mara's office in Clapham, south London, the shelves are lined with different editions. Morton and O'Mara made millions from it.O'Mara, 52, says the secret of his success has been to do royal biographies seriously, with rigorous research and no idle speculation or tittle-tattle. I sat there thinking, `Blimey! Where are we here?' " O'Mara is an old hand at ruffling the Royals. And of the High Court judge who originally put a temporary injunction on the book, he recalls: "He was speaking in hushed tones, saying he was very worried what the Queen might think of all this. Born in the US, he has lived in Britain for 25 years, but says he cannot get used to British deference to royalty. "Fergie is just a dim girl who happened to marry someone in the Royal Family," he says.