Research & Planning: Narration

In my film I would possibly like to add an audio track to add as a narration, similarly used here in Children of Men: http://www.youtube.com/watch?v=wCTgUq6hzUk
By using a sort of news reader announcing events it sets the scene in the film therefore the audience can get a grasp of what the genre is and what is about to possibly happen. It is incredibly effective if a soundtrack is not provided. This method could help me introduce what the film (or opening scene) is about and also allow me to be able to cut to the character in the scene's reaction therefore, introducing who the character is and what they are about by their reaction.