Looking at the map and bearing in mind East Dulwich and Herne Hill are in zone 2 it looks like the zone has been narrowed for our part of London. Whats the logic of why we are in zone 3 and East Dulwich and Herne Hill are in Zone 2. We must be nearer the city of London?

http://en.wikipedia.org/wiki/List_of_sta...are_zone_2

The border is theoretically a circle 5 miles from Piccadilly Circus, although Lewisham and North Greenwich make it into zone 2 because the rings are extended a little to the east and west.

East Dulwich station is just inside Zone 2. The border (when buses were included in Travelcard Zones) is the Goose Green roundabout.

Zone 4 starts at Cobbs Corner, which is why Sydenham is just inside Zone 3, although Crystal Palace is shared between 3/4 after it was decided to move it into 3 to keep costs down for passengers.

Simple answer why not