The origins of the Class 50 lie in an invitation from the British Transport Commission (BTC) to manufacturers to produce a design for a lightweight Type 4 diesel locomotive with a gross power output of at least 2500 hp. In order to produce a prototype quickly, English Electric based their design on that for their Deltic locomotives which were then in production. Unlike the Deltics, this design was powered by a single engine, the 16CSVT, a development of the 16SVT used in the Class 40 locomotives. Parts related to the contemporary Class 37s were also used. The result was DP2, a 2700 hp Diesel-electric locomotive weighing 105 tons and with a top speed of 100 mph.