Playing the Scarlett woman

In The Other Boleyn Girl she plays Mary, Henry VIII's mistress who is believed to have produced his son but never made it to queen. That honour went to her sister Anne (played by Natalie Portman) who was later executed for her efforts.

Then later this year she'll pop up as the ill-fated heroine in Mary Queen Of Scots, who was born a year after Mary Boleyn died in 1543.

"It's kind of interesting because this takes place some time later but the same bloodline so I guess I'm playing a distant cousin of myself," ponders Scarlett of her latest role. "It's a little bit twisted."

The luminous Danish-American star admits she only got a smattering of British royal history in her American education.

"I remember learning 'divorced, beheaded, died, divorced, beheaded, survived', that's what I learned about Henry VIII, but it was never fully explained," she laughs.

"Maybe because Natalie (Portman) and I are both involved with this project it'll entice the younger generation and maybe spark their interest in the subject, because it's a fascinating time in history."

Getting to work with Portman was a big part of the enticement to doing the film, says Scarlett. "I'd never had the opportunity to work on such an even playing field with a peer, being able to play siblings. It was a great opportunity for both of us."

The Other Boleyn Girl is written by Peter Morgan (of The Last King of Scotland fame) and based on Philippa Gregory's best-selling fictional account of Henry's sordid court - it is also the film debut of English television director Justin Chadwick.

It was filmed at several historical houses and beauty spots across England, including locations in Gloucestershire, Cornwall, Kent, Derbyshire and Somerset.

The Boleyn girls were two sisters of noble birth who ended up rivals for the notorious Henry, with Anne making it to queen but losing her head - and Mary fading into contented anonymity with her commoner second husband. There's debate as to who was older, but Mary was credited to be the prettier and Anne the more sophisticated.

Mary was banished from court when she married beneath herself and didn't have contact with Anne during the last two years of her life, which ended with her infamous execution in 1536.

Scarlett defends Mary as a woman trying to survive in a world when their position relative to men was everything.

"She was acting within the confines of the time, given that she was a woman," says the 23-year-old. "Mary was competitive and kind of wants what Anne wants and is slightly jealous. "You put a little piece of yourself in every character you do and I identified with her will to survive," she adds.

The young actresses were restricted by the heavy female costumes of the era, she reveals. "As modern women we're used to being able to move freely, to not think about what we're wearing. With these costumes, it's not only uncomfortable to wear but it affects how people move around you.

"The costumes were huge, it affects your intimacy and all these things. You feel very statuesque and vulnerable, which is a constant reminder of the restrictions that were placed on women of this time."

Mary famously caught Henry VIII's eye first and her affair with him was a court scandal at the time.

"I think Mary's happy to be in the king's favour all of a sudden. She gets swept away with the grandeur of it all. I tried to bring that out in my performance, that she was ambitious at the beginning," says Scarlett.

The film plays on the jealousy and ego of Mary, while Anne is depicted in a more sympathetic light. Nevertheless the two women fight for the king's affections with all the manipulations at their disposal.

The rivalry between the sisters was a powerful emotion to play with, says Scarlett. "Because we have such respect for one another as actors it was exciting to get to the depth of that. There's so much behind the tension."

Pulling off a good English accent was another hurdle, one she just about masters. "I've spent a lot of time in London and having family there, that was helpful to me. But it's definitely something you want to nail down early so you don't have to think about it when you're working."

The Other Boleyn Girl is being touted as a historical girl-power drama, which Scarlett isn't entirely happy with.

"As much as I wasn't particularly looking for a girl power kind of role I think maintaining integrity in a character is a positive thing for women to see. I think it's inspiring for women of all ages."

The film certainly allows her a break from being Woody Allen's latest muse. Recently she co-starred with Penelope Cruz and Javier Bardem in Allen's Spanish outing Vicky Cristina Barcelona. She has also completed the romantic comedy He's Just Not That Into You with Jennifer Aniston and Ben Affleck.

In her own life, Scarlett is rumoured to be getting engaged to current boyfriend, 31-year-old Canadian actor Ryan Reynolds.

A face of L'Oreal, the glamorous star says there's no preparation for major stardom. Despite working as a child actor, she catapulted to the big time after hit Lost In Translation in 2003.

"I don't think there's any preparation for sudden celebrity. I think you almost have a kind of slight nervous breakdown when that kind of media attention happens. You have to make these weird adjustments."

Recently she hit back at a celebrity magazine's allegation that she's had plastic surgery. "It was awful, I was willing to let them examine me. I really haven't had any."

On the political front Scarlett has been actively campaigning for Barack Obama in the hotly contested Democratic Party primary race. "It has been really inspiring just seeing all these young people going out and rallying," she enthuses.

Adding another string to her bow she will release her debut album later this year, singing 10 Tom Waits covers and an original song under the title 'Anywhere I lay My Head'. Is this a break-out career move?

"Who knows, I don't have any expectations about it," she says. "I just love to sing."