British Rail Class 50

The BR Class 50, universally nicknamed the Hoover on account of the distinctive howling sound produced by its English Electric 16CSVT engine under load, was a class of fifty Co-Co diesel-electric locomotives built by English Electric at their Vulcan Foundry works in Newton-le-Willows between 1967 and 1968. The circumstances of the Class 50's introduction were unusual in British railway history: the locomotives were not initially owned by British Railways but were hired from English Electric, which retained ownership while BR evaluated the class in traffic. This leasing arrangement, rare for mainline traction, reflected both English Electric's confidence in its product and BR's desire to test the 2,700 hp locomotive in service before committing to purchase.

The Class 50 was designed to work the West Coast Main Line north of Crewe to Glasgow, the section that had not yet received the 25 kV electrification that had transformed the London–Birmingham–Manchester–Liverpool routes. Until electrification reached the Scottish border and beyond, something more powerful than the 2,580 hp Class 47 was needed on the heavy Anglo-Scottish expresses, and the English Electric 16CSVT engine — a sixteen-cylinder version of the same engine family that powered the highly successful Class 40 and the Deltics — gave 2,700 hp in a Co-Co package that could manage the Anglo-Scottish grades at the required speeds.

All fifty locomotives were delivered in 1967–68 and immediately allocated to the LMR for WCML work, operating the principal expresses from London Euston to Glasgow Central, Edinburgh Waverley, and intermediate points. They performed well on this duty, and BR exercised its option to purchase the fleet from English Electric in 1973. However, by then the electrification of the WCML north of Crewe to Glasgow was under active development, and it was clear that the Class 50s would soon be displaced from their original role.

From 1974 BR transferred the entire Class 50 fleet to the Western Region to replace the ageing and increasingly unreliable diesel-hydraulic Classes 42/43 Warship and Class 52 Western on WR main-line express services. This transfer proved fortuitous for both the class and the WR. On the Paddington–Bristol, Paddington–Plymouth, and Paddington–Penzance routes, the Class 50 found its metier: challenging gradients, heavy express trains, and drivers who had grown up with the diesel-hydraulics and appreciated a locomotive with genuine character. All fifty were named after Royal Navy warships — perpetuating the naming tradition of the Classes 42/43 Warships that the 50s had replaced — and the class became one of the most popular diesel types among enthusiasts and enginemen alike during the 1980s.

A major refurbishment programme carried out at Doncaster Works between 1979 and 1984 rebuilt the entire class with updated electrical equipment and improved reliability, extending their service lives considerably. In their refurbished state the Class 50s worked WR expresses into the late 1980s alongside the High Speed Train, though the HST's dominance progressively restricted the 50s to secondary duties. Withdrawals began in 1987 and the last examples were retired from BR service in 1994.

The Class 50 is exceptionally well represented in preservation: eighteen examples survive, including several in mainline-certified condition. Among the most celebrated are 50007 Hercules, 50015 Valiant, 50017 Royal Oak, 50035 Ark Royal, and 50044 Exeter, the last of which is based on the Severn Valley Railway. The Class 50 Alliance, the principal preservation group, maintains several members at Kidderminster.