List of stations in London fare zone 8

Fare zones 7–9 are ancillary zones of the Travelcard and Oyster card fares scheme managed by Transport for London, used for calculating fares from some stations outside Greater London that are not in zones 4, 5 and 6. Travelcards are available on Oyster with validity in these zones. They are not included in the validity of National Rail out-boundary Travelcards unless mentioned in the Route section as "AAA LDN ZONE 7-9". Fare zones B, C, G and W, and the route out to Gatwick Airport, have fares set by National Rail train operating companies. The fare zones are outside Greater London, typically more than 16 miles (26 km) from Piccadilly Circus.

The zones extend in segments from the boundary of Greater London to the north and west into Hertfordshire and Buckinghamshire, to the east into Essex and Kent and to the south into Surrey and West Sussex. Unlike zones 1-6, they do not form a complete ring around London. They include eight London Underground stations on the Metropolitan line and some London Overground stations.

...
Wikipedia