The SR Q1 class is a type of austerity steam locomotive constructed during the Second World War. The class was designed by Oliver Bulleid for use on the intensive freight turns experienced during wartime on the Southern Railway network. A total of 40 locomotives were built. Bulleid incorporated many innovations and weight-saving concepts to produce a highly functional design. The class lasted in service until July 1966, and the first member of the class, number C1, has been preserved by the National Railway Museum.

Oliver Vaughan Snell Bulleid CBE was a British railway and mechanical engineer best known as the Chief Mechanical Engineer (CME) of the Southern Railway between 1937 and the 1948 nationalisation, developing many well-known locomotives.