In unearthed pictures from the ITV2 series, the 35-year-old actress looked completely different as her alter-ego Belle for the show which aired from 2007 to 2011.
In the sixth episode of the show, Billie was seen in a bright green underwear set with added white lace detail as she seduced a client for a saucy scene.
The former singer gave viewers a full flash of her pert derrière in a sex scene where she sat on top of a man in bed.
Billie was also captured mid-shot taking off her clothes, unveiling her cleavage as she stripped down to her risqué underwear.Related articles
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The actress added a lace garter around her well-defined thighs and she also wore pink gloves to complete her look.
The Beauty wore minimal make-up and sported brunette hair with a full fringe.
Billie has also starred in the likes of Doctor Who, Penny Dreadful and Yerma.
The mother-of-two’s most recent role sees her playing Karen Mars in the BBC Two drama Collateral.