BR Locomotive Design Office

'British Railways' (later the British Railways Board, and from 1965 simply 'British Rail') is used in this encyclopedia as a generic designer attribution for diesel and electric locomotive classes designed by central or regional BR engineering offices in cases where no single named designer is recorded. It covers the period from BR's formation by nationalisation on 1 January 1948 to the privatisation of the network from 1994 to 1997.

Through the steam era BR design was led by R. A. Riddles's team in the BR Standard programme; from the 1955 Modernisation Plan, locomotive design moved largely into private industry, with BR's role increasingly that of a sophisticated client and integrator. Specific regional design offices, BR Doncaster, BR Crewe, BR Swindon and others, continued to maintain detailed design responsibility for particular classes.