The Great Northern Railway (GNR) Class C1 is a type of 4-4-2 steam locomotive. One, ex GNR 251, survives in preservation. Much like their small boiler cousins, they were capable of reaching speeds of up to 90 mph (145 km/h). They were also known as Large Atlantics.

Under the Whyte notation for the classification of steam locomotives by wheel arrangement, 4-4-2 represents a configuration of a four-wheeled leading bogie, four powered and coupled driving wheels, and two trailing wheels supporting part of the weight of the boiler and firebox. This allows a larger firebox and boiler than the 4-4-0 configuration.