BR 10800

BR 10800 was a single diesel-mechanical Bo-Bo locomotive built in 1949 as part of British Railways' early post-war diesel trials programme, a period in which BR ordered a series of experimental main-line diesel locomotives from different manufacturers to evaluate configurations and technologies before committing to any standard design. 10800 was built by Hawthorn Leslie of Newcastle to a specification produced under the influence of Henry Ivatt at the London Midland Region, powered by a 827 hp Davey Paxman 16RPH engine driving through a mechanical transmission.

The locomotive was a Bo-Bo — two four-wheeled bogies, each with two traction axles — a layout that would eventually become the standard for British diesel electrics, though 10800's mechanical transmission placed it in a different category from the diesel-electric arrangements that would dominate. It spent its BR career on trials on the London Midland Region, never entering regular revenue service in any meaningful sense, and was regarded as underpowered and mechanically troublesome.

In 1958 BR effectively gave up on 10800 and it was sold to the Brush Traction company of Loughborough in 1962. Brush used the locomotive as a mobile test bed for developing the Sulzer 12LDA28 engine installation that would power what became the highly successful Class 47, one of the most numerous and long-lived diesel classes in British railway history. Once its usefulness as a test vehicle was exhausted, 10800 was scrapped. None was preserved.