Cara Delevingne wasn't cast in 'Paper Towns' because of her successful modelling career.

The film's director, John Green, insists the 23-year-old beauty's previous work had nothing to do with her landing the role of Margo.

He said: ''She did not get cast because she was a supermodel. In the movie, she looks like a kid. Cara's public persona has a lot in common with Margo. Cara is complicated, multifaceted, smart, talented and she is also very sensitive, which maybe we don't see as much in public.''

The 37-year-old filmmaker also suggested Cara's experience of fame helped her to channel her character's emotions.

He told the Observer newspaper: ''She is able to go to deep, difficult places when she is acting, and I was very impressed by that. There is a moment where Quentin says, 'I love you Margo', and Margo says, 'Love me? You don't even know me'. In her audition, Cara said that with such depth of feeling, it seemed to me that maybe she was a person who knew what it was like to have people love you and not know you.''