The British Rail Class 56 Type 5 Co-Co diesel locomotive was first introduced in 1976 to cope with the increased requirement for heavy freight. British Rail awarded the contract to design and build these new engines to Brush Traction in Loughborough, who subsequently sub-contracted the construction to Electroputere in Romania, due to the lack of capacity in their own works.
The initial 30 locomotives to be delivered from Romania suffered from transit damage and construction deficiencies and had to be extensively rebuilt before entering service. With this in mind the decision was made to build the remaining 105 locomotives in England, British Rail Engineering Ltd manufacturing them at their Doncaster Works (nos. 56031 to 56115) and Crewe Works (nos. 56116 to 56135). The design specification was based upon the Class 47 bodyshell, with the omission of redundant features such as the headcode panel.