The British Rail Class 432 (4-REP) electric multiple unit passenger trains were built by BR at York Works from 1966 to 1967 and in 1974.

Tests in the mid 1960s had proved that high speed main line push-pull operation was both feasible and safe.

The whole scheme also revealed a need for a small batch of locomotives to maintain connecting services between London (Waterloo) and the unelectrified area of Southampton Docks for the passenger Ocean Liner traffic.

To provide for this need, and keep the whole scheme within the limited budget available it was decided that 10 Class 71 2,550 hp (1,900 kW) straight electric locomotives operating on the South Eastern Division of the Region in the Kent area, that had become excess to operating needs be converted to Class 74.

As it transpired the locomotives as altered were fairly unreliable, and the Ocean Liner traffic for which they were primarily intended was rapidly vanishing.

The high powered (3,200 hp (2,400 kW)) EMU tractor units were classified 4-REP (Restaurant Electro-Pneumatic brake), the trailer units 3-TC and 4-TC (Trailer Control) and the push-pull equipped diesel locomotives were converted from 19 of the Southern's native BRCW type 3 1,550 hp (1,160 kW) fleet (eventually to become designated class 33/1).

In 1974, an additional four units were introduced to increase the frequency of the service and to provide cover for extended maintenance of the fleet.

[1] Surviving REPs saw an application of Network SouthEast flashes from 1986 onwards, while the Class 442 "Wessex Electrics" were being built.

The REPs were good performers in service, their maximum permitted speed of 90 mph (145 km/h) being easily exceeded even with a full load of two additional 4TC trailer sets.

During the late 1970s, speed tests were carried out between Woking and Basingstoke with a view to upgrading the permitted maximum to 100 mph (161 km/h) but this was never undertaken mainly due to the increased braking performance required.

In the mid 1980s, the decision came to replace the Weymouth line stock – not only because finance had become available to electrify the line between Bournemouth and Weymouth using new low-cost technology but also because the unpowered REP and TC cars were converted from Mark 1 coaching stock originally built in the early 1950s thus, by the late 1980s, British Rail was looking to replace them.

The 432 driving cars were relocated into the middle of the formation and had their leading ends repainted and their driver compartment doors locked out of use.

During the run formations changed regularly and renumbering of the units in the 19xx series was common, including the original 1901 and 1902 set numbers.