Sky Showbiz - Who's Up For Billie's Job?

She's Freema Agyeman, 26, and is currently filming the BBC's new drama Ruby In The Smoke, in which she plays a Victorian sleuth.

An insider told The Sun: "Freema is a fantastic actress... and she is more than capable of stepping into Billie's shoes to play the Doctor's new cohort.

"Don't forget, no one knew Billie could act before we gave her the job and she's proved to be a sensation."

OK. We'll see.

They also have a slide show of 16 other potential sidekicks.