Speaking to Time Out London magazine, 47-year-old filmmaker Martin McDonagh said: "There isn't anyone else who could play Mildred. There isn't anyone with that same integrity and forcefulness.
McDonagh was referring to Frances McDormand who just won the Golden Globe for best actress for her work in Three Billboards.
The film has received critical acclaim and has an Oscar buzz surrounding it. The 'In Bruges' filmmaker knew his leading lady would be the best actress of 2017.