3. Keira Knightley
Keira Knightley is perhaps still best known for her role as Elizabeth Swann in the Pirates of the Caribbean series, but has taken on many varied roles over the years, being no stranger to period pieces with her parts in Atonement and Pride and Prejudice, something which would no doubt help her to play a member of royalty, although obviously in a more modern film. Knightley undoubtedly has the perfect accent required to play Kate Middleton, along with the natural beauty that, like Emily Blunt, has led her to become no stranger to playing high-profile historical figures, including that of Georgiana, Duchess of Devonshire in the film, The Duchess. This part will have prepared Knightley for the pitfalls that can be associated with playing a real-life person, albeit one that has long since passed away, and would allow her to slip easily into the role. Of course, we can also take comfort in the fact that Love Actually taught us that she really knows how to pull off a wedding scene!