It is the beginning of the end of paper rail tickets for some Southern passengers travelling into London.
Commuters using the Brighton line into the capital will be able to use smart-cards, similar to Oyster-cards, at East Croydon, Clapham Junction, London Victoria and London Bridge.
The scheme will be widened out to all London stations as of next year.
Baroness Kramer launched the new scheme yesterday.
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Vodafone has been fined £4.6 million by the industry regulator for "serious and sustained" breaches of consumer protection rules.
Wednesday morning's weather for the east of the region
Wednesday morning's weather for the west of the region