Mallard is an A4 class locomotive designed by Sir Nigel Gresley located at National Railway Museum, York. The A4s were built to power high-speed trains in the late 1930s, and their shape was honed in a wind tunnel to help them cut through the air as cleanly as possible. This powerful, aerodynamic masterpiece rocketed to 126mph in 1938, a steam speed record that was never surpassed.

The locomotive is 70 ft long and weighs 168 tons, including the tender. It is painted LNER garter blue with red wheels and steel rims.