The British Rail Class 319 is an electric multiple unit passenger train built by British Rail Engineering Limited's Holgate Road carriage works for use on north–south cross-London services. These dual-voltage trains are capable of operating on 25 kV 50 Hz from AC overhead wires or 750 V DC from a third rail.

Built in two batches in 1987–88 and 1990, the units were primarily used on the then-new Thameslink service from Bedford to Brighton and various other destinations south of London. The majority of the fleet remained in use on the Thameslink route after its reshaping and privatisation in 1997. Some of the fleet was also used by Connex South Central and latterly Southern on various services operating out of London Victoria, including flagship expresses to Brighton.