The school (or the LA in its admissions guidance) should publish in its oversubscription criteria how distance is measured, but it would be from your individual address. Some areas / schools use "as the crow flies" distance, others shortest safe walking route.
Hi, thanks, the school we are interested in uses "as the crow flies" distance, I have gone on a google map which offers this choice and every time I key in my address it just takes the point to a central area to anyone in that particular postode. So unless their system works differently to the google maps one, I assume we will all stand the same chance and if oversubscribed, our names will just be drawn out randomly. Not sure if this is accurate, but maybe their system works differently.