The history of rail transport in Great Britain 1923–1947 covers the period when the British railway system was run by the Big Four group of companies – the London, Midland and Scottish Railway (LMS); the Great Western Railway (GWR); the London and North Eastern Railway (LNER); and the Southern Railway (SR). The period includes the investment following World War I; the rise in competition from the roads in the 1920s; development of steam locomotives capable of sustained 100 mph (160 km/h) running; the Great Depression of the 1930s; World War II and its aftermath; and the lead up to nationalisation during 1947.