The 27-year-old stunned the world when she stepped out with the short, glowing locks in May (16), and the star now reveals the wild hairstyle was a "character choice" for her upcoming moving Okja, which she has been shooting in South Korea.

"My director (Joon-ho Bong) had this idea of having my hair be a very vibrant red/pink/watermelon colour," she tells U.S. website Harper's Bazaar. "We haven't finished filming so I'm kind of riding the wave of the red hair right now in terms of everything else that I have to do with The Last Tycoon press and you know, regular life. I'm really loving it. It's turning into a thing for me."

The Last Tycoon is a new Amazon Studios period pilot set in the 1930s, in which Lily portrays the character Cecelia Brady. When dressing up in costume on set for the historical drama, Lily and her style team went a totally different style route, going for tamed restriction versus the untamed Okja aesthetic, and the entire process took a considerable amount of time to complete.

"It took about two hours," she recalls of transforming into Cecelia. "It's because of those pin curls! They take so long to set. Then makeup would have to cover my tattoos. Then to put the undergarments on and the top coat and the accessories and the shoes, (the layers were) very genuinely difficult to wear."

Despite the effort it took to get into costume, similar to what she is experiencing on the Okja shoot, Lily feels her style has improved after learning new wardrobe techniques from The Last Tycoon costume designer Janie Bryant, who also ran the wardrobe department for hit period TV drama Mad Men.

"I learned how to incorporate a cute Peter Pan collar on a dress and not make it look juvenile," she laughed. "And hats, I love hats, I'm such a fan of hats. You don't wear a fascinator (headpiece) everywhere you go, but there are ways to incorporate old Hollywood nuances into your looks today but also edge it up."