Change of setting

I knew the book before I saw the movie and, given how involved the author was with the production, I was surprised how different it was - especially the change of location from somewhere in the South (Surrey, from the place-names mentioned although never confirmed) to Lancashire and changing the children from a fairly well-off family to poor. Also switching the focus from the middle child to the oldest and changing their names. Seemed less an adaptation of the book and more someone else telling a story having been told a one-paragraph summary of the book. Any thoughts?

www.amazon.co.uk/Adam-Greenwood/e/B00A681FH8
www.amazon.com/Adam-Greenwood/e/B00A681FH8