"Mizter T" wrote

The relative savings afforded by avoiding zone 1 for journeys within
London are perhaps comparable - again these are prices for annual
seasons:

Purley* to London Terminals £1,448
Zones 1-6 Travelcard £1,904
Zones 2-6 Travelcard £1,296

(*Purley price applies to any zone 6 Southern station to 'London
Terminals')

It certainly pays to avoid zone 1, as it does with 'London
Terminals'.

and in some cases it can be worthwhile buying the Travelcard to Z2,
decamping from the train at a Z2 station and completing the journey into Z1
by bus.

Peter