She is best known to thousands of children and parents as Rose Tyler from hit TV series Doctor Who.

But now former teen pop-star Billie Piper, is set to ditch her girl next door image after being lined up to play Belle de Jour - the infamous high class prostitute who made a fortune from chronicling her sexual exploits on the internet.

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Belle de Jour, whose real identity is only known by a handful of people, earned a six-figure book deal after her on-line diary about her sexual adventures became a massive draw with internet users, getting thousands of hits a day.

Now Piper, 24, is set to bring to life the lurid tales - described by some as a "top-shelf Bridget Jones" with plans for the C4 drama.

In the book Belle de Jour goes into graphic detail about her sexual liaisons with a range of men - including an investment banker, a senior law enforcement officer and a psychoanalyst.

But the diaries are as much about the day to day preoccupations of Belle de Jour, who offers fashion tips and talks about mundane concerns such as having her house redesigned.

The decision of Piper, who is also about appear on TV screens as Fanny Price in an adaptation of Mansfield Park on ITV, to take the part will be seen as a clear move to make a break with her clean cut image and show the world once and for all she is a fully-grown up actress.

Friends say she is "desperate" to play the part of Belle de Jour, with Channel 4 expected to green-light the project in the coming weeks.

Piper, who shot to fame as a 15-year-old pop star, who was the youngest performer to have achieved a number one debut single and followed that up with another chart topper in the same year.

She famously tied the knot with DJ Chris Evans in 2001 in Las Vegas - they split three years later in 2004.

Piper has recently just began a new relationship with Laurence Fox, son of actor James Fox, who co-stars with Piper in current West End production Treats.

He left his live-in girlfriend of six years just before Christmas. At the same time Piper broke up with lawyer Amadu Sowe, her boyfriend of two years.

She has previously appeared in the BBC's Canterbury Tales: The Miller's Tale in 2003 and also won rave reviews for her perfomance in Bella the Boys.

Belle de Jour, named after the famous French film from the 1960's, which starred Catherine Deneuve, claims to be an English Jewish woman in her 20s who studied arts at university, who lives in Islington but is originally from Yorkshire.

She is well-educated, familiar with French and Italian classics as well as Shakespeare, wears Chanel nail varnish and shops at Harvey Nicholls while boasting a stunning array of lingerie.

The real identity of Belle de Jour has become the subject of frenzied media speculation - with many believing it to have been the work of a novelist or journalist.