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 highly unusual and controversial design represents the ultimate development of the British 0-6-0 freight engine, capable of hauling trains that were usually allocated to much larger locomotives on other railways. Nicknames for the class included "Ugly Ducklings", "Coffee Pots", "Charlies", "Biscuit Tins", "Biscuit Barrels", "Clockworks" and "Frankensteins".

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.