In 1948, the Big Four railway companies, along with their associated join companies, were nationalised to form British Railways. Although electric and diesel traction were creeping onto the network, steam power still ruled the rails.

World War II

During the war, the railway system was used more than at any point in history. Troops and armament were sent across the country and supplies that kept the county alive were transported from the ports to the cities on top of their normal freight and passenger duties. To eliminate loses from competition, the Government stepped in to pool all revenues the split them between the four companies based on size. Above a certain level, the treasury kept half the money. Above another level, the railways saw none of the fares.

Railways were major targets for air raids, and while the infrastructure was often quickly repaired, it still took its toll.

On top of this, the materials required for the maintenance and expansion of the system were needed for the war effort. This left the railways in a periolous state by the end of the war