More commuters will be able to use Oyster pay-as-you-go travelcards on London main line rail services from January, it was announced today.
The extension of the scheme, which will also include Thames Clipper river services, will particularly benefit travellers in south and north east London.
Oyster cards, used by most Tube and bus passengers in the capital, will, from January 2, be accepted on all Greater London services operated by eight main line train companies.
They are Chiltern, National Express East Anglia, London Midland, First Great Western, First Capital Connect, Southern, Southeastern and South West Trains.
Oyster pay-as-you-go will also be accepted on Greater London services run by the London to Tilbury and Southend train company c2c as well as Grays, Chafford Hundred, Purfleet and Ockendon stations in Essex.
London Mayor Boris Johnson, said: "I am delighted to be able to announce that the Oysterisation of all London's commuter rail services is to become a reality.
"This, combined with the news about Thames Clippers services, means Oyster will be all over the capital. It truly will be the only ticket Londoners need to get around town."
Transport Secretary Lord Adonis said: "Oyster pay-as-you-go will transform travel in London as for the first time passengers will be able to travel seamlessly across the network and switch between Underground and all overground rail services."
Sharon Grant, chairman of passenger group London TravelWatch, said: "This is great news and a new dawn for passengers in London."
But Caroline Pidgeon, Liberal Democrat London Assembly Transport spokesman, said today's announcement "fell far short of what Londoners deserve".
She added that rail travellers would face "serious hassle each and every time they wish to travel out of the zone covered by their season ticket".