In the months that followed the publication of the document Modernisation and Reequipment of British Railways in 1955 by the British Transport Commission (BTC) a number of diesel and electric locomotives was ordered.
Initially, the British Transport Commission identified three main power ranges for its new diesel locomotive fleet. Type A covered 8001,000hp for freight duties, Type B 1,000hp1,250hp for mixed traffic work and Type C was for locomotives of 2,000hp and over for what were described as ‘heavy duties’. It proposed building ten Type C locomotives in BR workshops and these would form the basis for future BR standards. These locomotives were part of 160 approved in principle for construction on 17th November 1954. Construction was authorised by the BTC on 17th February 1955 as part of the 1956 Building Programme with an initial estimated cost of £840,000.
Fourteen diesel-hydraulic locomotives were also ordered and these 174 diesel locomotives were part of the 1956 and 1957 Building Programmes. The intention was there should be a virtual standstill of three years
