SR West Country and Battle of Britain Classes - Background

Background

The financial success enjoyed by the Southern Railway during the 1930s was based on the completion of its London suburban electrification scheme in 1929 and the subsequent electrification of the main lines to Brighton and the Sussex Coast and to Guildford and Portsmouth. Plans to electrify the main lines to the Kent coast resorts and Channel ports followed by the South Western main line to Southampton and Bournemouth had been made, but were interrupted by the outbreak of the Second World War.

Despite electrification plans, the Southern Railway's less heavily used lines in the West Country beyond Salisbury did not merit this cost. Lines in Devon and Cornwall were meandering, heavily graded, and although with heavy summer holiday traffic were lightly used during the winter months. The seasonality of railway traffic meant that the West Country branches were worked by the ageing T9 class 4-4-0 and the versatile N class 2-6-0, which could be better utilised on mixed-traffic services elsewhere. As a result, an order was placed with Brighton railway works in April 1941 for twenty passenger locomotives of a type to be determined. However, the works was involved in heavy freight locomotive construction for the war effort, resulting in a four-year delay.

During 1943, Bulleid began planning for the post-war locomotive requirements of the railway and identified the need for a stop-gap steam locomotive design for those main lines in South East England scheduled for electrification had the Second World War not taken place. Although the new Merchant Navy class was available for the heaviest Continental expresses, the resumption of frequent passenger services over poorly maintained infrastructure following the war would require a lighter locomotive with wider route availability.

At the same time there would be a continuing need for fast freight locomotives capable of operating on both electrified and non-electrified routes without impeding the intensive use of the system by passenger trains. Suburban electrification used electric multiple units, which had no equivalent freight design. Although Bulleid built two prototype electric locomotives in 1941 these were as yet unproven, and freight haulage would be undertaken by steam traction for the foreseeable future.