Lily James is "having a blast" playing Pamela Anderson in 'Pam & Tommy'

A source told The Sun on Sunday newspaper: "Lily’s having a blast getting into character and playing dress up with the fake chest piece.

"The boobs really help her get into character and she loves walking around in them."

Lily - who previously played Lady Rose in 'Downton Abbey' - has been spotted sporting blonde locks and a red swimsuit while filming the upcoming series, which focuses on Pamela's relationship with her ex-husband Tommy Lee.

The actress previously admitted that her body noticeably changes when she doesn't exercise.

She explained in 2016: "I go through phases of exercise, and I do begin to feel bad if I’m not moving my body and stretching. My boobs get really big when I don’t exercise."

Lily is also "grateful" that she's surrounded by make-up experts on set.

She said: "We're so lucky to get professionals to do our make-up.

"It does make a huge difference because of the ways in which they shade and contour. It is like being a magician, being a great make-up artist, so I do feel really grateful. The transformation from when you get in the chair to afterward is really huge."

The Hollywood star revealed her biggest beauty regret, too.

She explained: "I used to put concealer on my lips, almost like taking nude to like a whole other level. You'd basically be blocking out your lips. I don't know what that was about, that was 2000 or something. I won't ever conceal my lips again."