Mallard is an A4 class locomotive designed by Sir Nigel Gresley. 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—making speeds of 120mph and above possible.
This powerful, aerodynamic masterpiece rocketed to 126mph in 1938, a steam speed record that was never surpassed.