'Doctor Who' alumna Billie Piper has been tagged to play the lead in a British TV adaptation of 'Belle de Jour,' the blog-turned-book from an anonymous London prostitute, reports Piper is best known in the States as the most recent Companion of the Doctor, though prior to her stint on the TARDIS, she also had a successful career as a pop singer. Now that the world has seen her acting abilities, she is well on her way to film superstardom.