British Rail Class 313/3

The Class 313/3 is the subclass designation for Class 313 sets allocated to the Southern Region and operated predominantly in 750 V DC third-rail mode on South London suburban services, working routes including Watford DC line services operated by Chiltern Railways and various Southern Coastway services. As with the 313/2 subclass, the 313/3 designation reflects operational allocation and power supply configuration rather than any fundamental mechanical difference from the original Class 313 build.

For the full design history, technical specification, fleet information, and the story of the Class 313's pioneering dual-voltage capability, see the main Class 313 entry.