The school also functioned as an agency and took students to London to audition for acting jobs. She participated in over 20 of their stage productions, but was rarely selected as the lead due to her weight. While filming, an off-hand comment from the director Diarmuid Lawrence about the likeness between her and the actress who played her mother prompted Winslet to lose weight. Film breakthrough Peter Jackson gave Winslet her first film role as a teenage murderess in Heavenly Creatures Winslet was among girls to audition for Peter Jackson 's psychological drama Heavenly Creatures , and was cast after impressing Jackson with the intensity she brought to her part. She prepared for the part by reading the transcripts of the girls' murder trial, their letters and diaries, and interacted with their acquaintances. Impressed by her reading, Thompson cast her for the much larger part of the recklessly romantic teenager Marianne Dashwood.