British Railways (BR), which from 1965 traded as British Rail, was a state-owned company that operated most rail transport in Great Britain from 1948 to 1997. Originally a trading brand of the Railway Executive of the British Transport Commission, it became an independent statutory corporation in January 1963, when it was formally renamed the British Railways Board.
British Railways was formed on 1 January 1948 as a result of the Transport Act 1947, which nationalised the Big Four British railway companies along with some other (but not all) smaller railways. Profitability of the railways became a pressing concern during the 1950s, leading to multiple efforts to bolster performance, including some line closures. The 1955 Modernisation Plan formally directed a process of dieselisation and electrification to take place; accordingly, steam locomotives had been entirely replaced by diesel and electric traction (except for the narrow-gauge Vale of Rheidol Railway tourist line) by 1968. On 1 January 1963, the British Railways Board was created to manage the railways as a successor to the British Transport Commission.