Darryl Chamberlain BBC News Online

Sean Smith admits he thought Kylie Minogue would be a one-hit wonder when she was just a soap star chancing her arm on the music scene in the late 1980s.

In fact, in her native Australia, she was known as "Dannii Minogue's big sister" as the younger sibling was a TV star before Kylie hit the small screen.

A decade and a half later, the celebrity biographer has completed a lovingly detailed - if more than a little scurrilous - biography of one of the world's most famous singers.

He says her secret is the ability to change her image whenever she needs it - a lesson she learned from her days with British production trio Stock, Aitken and Waterman (SAW).

Not quite indie Kylie: With John Peel in 1988

"She's a great survivor, and she's got the courage to change her image and to surround herself with good people - something she's always done, even at SAW," she says.

Smith credits her success to a "team Kylie" - including the singer, manager Terry Blamey, and stylist William Bailey.

But as well as ex-boyfriend Michael Hutchence, he says singer Nick Cave also played a pivotal role in steering Kylie away from being just a pop puppet.

"Hutchence encouraged her to have her own input, and that was further promoted by Cave.

Poetry Olympics

"He persuaded Kylie to go on stage at the poetry Olympics in the mid '90s and, she started reciting the lyrics to I Should Be So Lucky, which gave the song irony for the first time.

"Cave was a big creative influence and Where The Wild Roses Grow is one of her favourite records. It startled everyone and the video saw her float like a dead Orphelia in a lake.

"She has credited Cave with giving her the chance to do different things."

Sibling rivalry: Dannii was more famous as a child

But ultimately, it's Minogue's ambition which has set her out from the crowd - early in her career, she paid for recording sessions out of her Neighbours salary.

Most recently, he thinks signing up with EMI was the turning point in her career - coming after a disappointing period with DeConstruction records.

"It put her next to Robbie Williams, gave her street cred, a whole new audience to combine with her loyal, very gay-based audience who she's carried with her all along, and she's built on that.

"EMI have given her commercial clout, and links with the United States - where she's finally started to do well."

In the book, he compares Kylie with Madonna - as many have done - and the late Diana, Princess of Wales, a link which appears rather tenuous in print.

Michael Hutchence was a huge influence on Kylie

"In the late '80s and early '90s Diana was everywhere, forefront of people's thoughts about style and fashion. Since her death, the media have looked elsewhere and Kylie has been a good choice for them because she's at the height of her appeal."

Madonna

He feels the Madonna comparison has ran its course to an extent.

"Madonna is older [she is 41] with two kids and seems settled. When Madonna was Kylie's current age [33], they were very similar, neither were married, no children, and at similar points in their careers.

"I'm sure Kylie is sick of being compared to Madonna - it happened when she changed from the girl next door."

Winner: Kylie Minogue at the 2002 Brits

Smith found the coincidences to be "so great", he published a detailed list of similarities in the book.

"Both had number ones with the title Fever - one a single, the other an album, and there turned out to be about 20 similarities."

He is sure Kylie will go on to follow Madonna in enjoying a long career.

"Madonna has passed 40 and is as a big as ever. I can even see Kylie playing in the West End in 10 years - my vision for her is being Liza Minnelli.

"In the future, I'm sure she'd like to crack the film world where she hasn't had much success, and try some acting when she nears 40.

"I had a star chart done for the book and it says 2008 will be a year of great importance - that's when she hits 40."

Kylie Confidential is published by Michael O'Mara Books, priced �16.99.

Click here to read a review.