The movie, W.E., tells parallel tales about Wallis Simpson in the 1930s and a contemporary woman called Wally Winthrop, who has romantic problems of her own - in addition to the fact that she's obsessed with the Duchess of Windsor's life.
Abbie, who starred opposite Ben Whishaw in Jane Campion's film Bright Star, will play the part of Wally once negotiations have been finalised.
Vera Farmiga will portray the Duchess (as revealed here first).
At the supper following last Sunday's Orange British Academy Film Awards, Vera told me her deal for W.E. had not been completed.
The participation of both actresses depends on who is cast in the two main male roles - Edward VIII, who became the Duke of Windsor after he gave up the throne for the woman he loved, and a Russian security guard, who sexually satisfies the married Wally.
The W.E. script has shown considerable improvement compared to an earlier version by Madonna and Alex Keshishian that I saw last year - there have been many drafts.
Madonna travels to Los Angeles early next month to meet with potential leading men. Then she'll head to London to inspect actors to play Edward.
The film will shoot from June on locations in London and the Home Counties, with short forays to New York and the South of France. Vera will also be in Los Angeles around the same time as Madonna.
She's a contender in the best supporting actress category for her performance, opposite George Clooney, in Jason Reitman's acclaimed best picture hopeful Up In The Air.
Australian-born Abbie first came to major attention in the film Somersault six years ago, as did Sam Worthington (who plays Jake in James Cameron's Avatar).
The addition of top producers David Parfitt and Colin Vaines gives the W.E. project a touch of class.
Source: Daily Mail