Rebecca Rubin Film and Media ReporterFinally, fans of the royal family get to hear Kristen Stewart’s take on Princess Diana’s iconic accent. In the first full-length trailer for “Spencer,” an upcoming biographical drama about the beloved figure, the American actor channels British royalty with ease.Directed by “Jackie” filmmaker Pablo Larrain, “Spencer” grapples with Diana’s decision to end her marriage to Prince Charles (portrayal Jack Farthing).