Class D3/12 (SR/English Electric 350hp Diesel-Electric)

In the latter years of the 1930s the Southern Railway, as with the other railway companies, began to experiment with diesel traction for shunting. These three locomotives were very similar to locomotives built a couple of years earlier by English Electric and Hawthorn Leslie for the LMSR. One key difference being larger diameter wheels to allow safe operation on lines with raised third conductor rails [1].

Information
Number built:	3
Built:	1937
Builder:	Southern Railway Ashford Works / English Electric
Motor:	English Electric 6K diesel
Power:	350 hp (260 kW)
Wheel arrangement:	0-6-0

The shunters had a top speed of forty-eight km/h to allow for trip working as well as yard shunting. The shunters quickly proved their worth over steam shunters, although they were more expensive to build the running costs over a steam locomotive were much lower [3]. The three shunters were used by the War Department during the Second World War but were returned to the Southern Railway and then British Railways after the end of the conflict. They were withdrawn from service in the mid-1960s though one survived in departmental use until 1970. 

Following the war, twenty-six similar locomotives were built which became the Class 12.

Number 2 in Southern colours [2]

[1] Brian Haresnape, Diesel Shunters (Ian Allan, 1984) p. 25

[2] "Driving a diesel-electric locomotive", Meccano Magazine (April 1945) p. 112

[3] Colin J Marsden, Diesel & Electric Locomotive Recognition Guide (Ian Allan, 2011) p. 4