In season four, we really get to see Princess Diana go from a relatively average teenager to an independent young 20-something. Although this time span proves to showcase an emotional evolution for Diana, her hair doesn't significantly change. "Emma's own hair colour is really similar to Diana's natural hair colour, but Diana's haircut was what defined her look, even un-styled it is unmistakably her." Hall said. "Her wigs throughout the season all have precisely the same 'Diana cut' but vary in colour and styling, becoming progressively blonder and more glamorous [and] voluminous."