Class 307 / PCV

The Class 307 EMU, originally known as the AM7, was built for Liverpool Street-Southend services. Originally they operated off 1500V DC overhead supply but in the early 1960s were converted to AC, first 6.25kV and later the standard 25kV [1]. They were built to the then-standard EPB style of Southern Region though operated on Eastern Region rails.

Information
Number built: 128 (32 4-car sets)
Built: 1954-56
(PCV conversion) 1994-96
Builder: BR Ashford/Eastleigh
(PCV conversion) Hunslet-Barclay
Engine: 4 GEC WT44 traction motors (1500V DC OLHE later 6.25/25kV AC OLHE)
Power: 700 hp (520 kW)
Formation: (original) Driving Trailer Standard Open (DTSO)+Motor Brake Standard
(MBS)+Trailer Composite (TC)+Driving Trailer Standard (DTS)
(AC conversion) Driving Trailer Brake Standard (DTBS)+
Motor Standard (MS)+TC+DTS
(refurbished) DTBS+MS+Trailer Standard (TS)+Driving Trailer Composite (DTC)

The Class 307s were refurbished in the 1980s which introduced gangways between the vehicles, improved interiors and new bogies. They continued to be used on Great Eastern routes throughout the 1980s, some also working on the Wakefield Line for a time. All were withdrawn from passenger service in the early 1990s.

Originally it was planned to rebuild the Class 307s for parcel traffic as the Class 300 but the Class 325 was built instead for this work. However 42 were rebuilt as Propelling Control Vehicles (PCV) for use on the end of locomotive hauled mail trains (the other end from the locomotive obviously) with the cab allowing for the train to be controlled at slow speeds [2], the PCV itself is unpowered. All but 2 were withdrawn from use in the early 2000s and many scrapped though 20 remain in storage around the country. One PCV has also been preserved as well as an unconverted driving trailer as shown below.
Preserved 307 123 DTSO at the Electric Railway Museum

Front view of 123

[1] Alec Swain, Overhead Line Electric Multiple Units (Ian Allan, 1990) p. 28
[2] Colin J Marsden, DMU and EMU Recognition Guide (Ian Allan, 2013) p. 221