Interavailabilty
Upminster, Barking, West Ham and Fenchurch Street (for Tower Hill) are also served by c2c. Tickets are interavailable between the two operators, and Oyster cards (including pay-as-you-go) are accepted on this part of c2c's route. South West Trains services occasionally run on the District line's Wimbledon branch between East Putney and Wimbledon when there are engineering works or problems on the main line, although the trains do not call at any of the intermediate stations.
Read more about this topic: District Line