Clearly she hasn't let her first pregnancy hold her back, as the actress tantalises viewers by losing her top and peeling off her jeans in a promotional advert for the new show.
Billie leaves little to the imagination as she wriggles out of the clothes, and replaces them with just a trenchcoat and a pair of high heels.
Going: Billie strips off her top in the back of a limousine in the promotional video for ITV2 show The Secret Diary of A Call Girl 2
Dr Who star Billie, 25 - high-class hooker Belle in the show - is left in revealing black underwear as she provocatively coats her lips with gloss in the saucy scene.
Billie is seen striding down the street before hopping into a parked limousine where she begins to ready herself for an evening's work as alter-ego Belle.
The actress' swelling bosom somewhat gives the game away, but all other signs of her pregnancy are concealed.
The series returns next month.Belle's back: Billie is reprising her role in the hit series, and has carried on filming even throughout her first pregnancy
The actress is married to actor Laurence Fox, and their child is due at New Year
Meanwhile Billie said she is suffering cravings for Greek food during her first pregnancy.
And actor husband Laurence Fox’s culinary skills are helping satisfy her hunger pangs.
‘Billie is always hungry, so Laurence is cooking non-stop,’ a source said.
‘He’s doing moussakas, Greek salads and meze.’
The couple are 'over the moon' about their baby, due at New Year, around the time of their first wedding anniversary.