The Class 50 locomotives, built by English Electric at the Vulcan Foundry in Newton-le-Willows between 1967-1968 were the last purpose-designed mixed-traffic locomotive built in the UK. 50 examples were built in total. Upon their introduction they were used on the West Coast Main Line (WCML). The aim was to speed-up passenger timings on the then non-electrified portion up to Glasgow, and to haul express passenger trains at 100 mph. By 1974, the entire line had been electrified so the locomotives were re-deployed to other regions as had been planned. When delivered, the Class 50s were leased to British Rail by a subsidiary of English Electric. They were later sold to the British Railways Board.

The Class 50s proved to be incredibly powerful, indeed following the full electrification of the WCML and the introduction of more powerful DMUs in the late 1980’s they were almost pointlessly powerful, and they began to be withdrawn as their roles were handed to more efficient DMUs. All examples of the Class were named which was rather unusual for corporate BR diesel locomotives, and in the end 18 examples have been preserved.

Locomotive 50040 started life as D440 and would go on to receive the name Leviathan after a Royal Navy ship in 1978. The locomotive would go on in service until 1990, at which point it was withdrawn and stored awaiting confirmation of its fate. In June 2008, with most useful parts removed, the cutters torch descended on 50040 at Sims Metal Management in Halesowen some 80 miles from where it was constructed.