Designed by Charles Fairburn, during his very short reign as CME of the LMS, a total of 277 of these tank engines were constructed between 1945 and 1951 at the LMS Derby Works and, after Nationalisation, at the former Southern Railway works in Brighton, where 41 of them were built.

The building of locomotives during the Second World War was restricted and it was during this time that the only class attributed to Charles Fairburn was built. With additional locomotives being required following the end of the war, Fairburn took time to evaluate the Stanier locomotives by conducting a series of trials. As a result, he calculated that a reduction in the coupled wheelbase would be beneficial, as would a reduction in the overall weight. Fairburn managed to reduce the total weight by 2.5 tons to 85 tons 5cwt.

As part of the 1948 Locomotive Trials, two Fairburn tank locomotives (2198 and 2199) were sent to work on the Southern Region. The Central and South Eastern Divisions contained a number of non-electrified lines over which several ageing pre-Grouping locomotives were used. They obviously impressed and, as a result, production of them started at the Brighton Works, The Brighton built engines went into service on the Southern Region, allowing many older locomotives to be retired. They remained until 1960 when BR Standard 2-6-4Ts from the London Midland Region were exchanged for the Fairburn tanks.

Elsewhere, the Fairburn tanks were spread far and wide. The first Fairburn tank was withdrawn in 1961 and the last in 1965. In its formative years, the Lakeside & Haverthwaite Railway secured their two locomotives (42073 and 42085) from British Railways for preservation in 1968. Once the line had been secured they moved to Haverthwaite where they remain in service on the line to Lakeside, on the southern shore of Lake Windermere.