BR pilot scheme 1200bhp type 2 design built to test a Crossley 2-stroke diesel engine in comparison to the 4-stroke types used in all other design submissions. The highly successful EMD engines widely used in the US and now found in class 59/66/67 locomotives being a 2-stroke design. To spread the locomotives weight to meet British Railways axle loading specifications an unusual 5-axle layout of one 3 axle C and one 2 axle B trucks was used, with motors driving all 5 axles (indicated by the o suffix). Hence the Co-Bo designation. Initially deployed on the Condor express container freight service reliability issues soon saw the class redeployed to less onerous duties where their failures would cause less trouble. One locomotive is preserved for future generations to discover the quirky but ill-fated Co-Bo.