Naomi Watts got into her royal role as Princess Diana in her upcoming movie, Diana, today in Hertfordshire, England. She arrived on set wearing a heavy robe that she later shed to reveal a modest blue suit. We first caught a glimpse of Naomi as Princess Diana in early June when she reported to set in London, and she has been hard at work since. She did, however, break for a Summer vacation. Naomi shared PDA with Liev Schreiber and spent downtime with their two sons during their family getaway to Saint-Tropez in mid-July. She is now back to focusing on Diana, which details two years of the late princess's life.