Looking at the latest version of the TfL High Frequency Services
map[1] Alperton, Boston Manor, Hanwell, Drayton Green and Castle Bar
Park appear to have been moved from zone 4 to zone 3. Changes afoot or
simple mistake? (T5 aside, there's not much that needs changing map-
wise in west London that might have resulted in an error...?)
~cj

[1] http://www.tfl.gov.uk/assets/downloa...rvices-map.pdf
It's the "June 2008 web update" according to the bottom right of the
map