I really wanted Rachel [from the Girl on The Train] to be purely fixated on fantasy and on her ex-husband.I didn't want her to be embarking on romance, touching people; I wanted her purely in the realm of fantasy and frustration and dreaming and sadness.

I wanted to keep the complexity of the female experience in the film as much as it is in the book, and the subject of not wanting a child is a very interesting subject, one that's not dealt with very much actually.However that complexity was not serving the story of what became the film [The Girl on the Train].

The gaslight of the film [The Girl On The Train] became something that really needed to be dramatized more than the book did, because it wasn't going to read as strongly on screen.

I really wanted Rachel [from the Girl on The Train] to be purely fixated on fantasy and on her ex-husband.I didn't want her to be embarking on romance, touching people; I wanted her purely in the realm of fantasy and frustration and dreaming and sadness.

I needed to enhance the outward threat to Rachel.In the book [Girl on the Train], her inner threat is so strong; the fear of herself and her inability to remember and the false memories. In the film [Girl on the Train]I wanted to increase the exterior threat. So that's why Allison's part was bigger and was an important part of the climax of the film.

I always thought that the location of this film [Girl In The Train] was on the train and inside her imagination, and her loneliness and her gaze out the window.Although it was set in England, it didn't feel to me like an overly English book. In terms of the use of cultural references, it was not extreme, so it was very simple to go from England to America in the adaptation.

It's what you do when you have Allison Janney.My jaw-dropped at her performance. You think that part is sort of a regular part until she steps into the shoes of the officer. She just filled it with such dimension and by giving her the whole shebang, the whole police thread, I think it was the right choice.