Number 4468 Mallard is a London and North Eastern Railway Class A4 4-6-2 Pacific steam locomotive designed by Sir Nigel Gresley and built at Doncaster, England in 1938. It was designed as an express locomotive with a wind-tunnel-tested, aerodynamic body that allowed it to reach speeds of over 100 mph (160 km/h). It was in service until 1963 when it was retired, having covered almost one and a half million miles (2.4 million km).
It was restored to working order in 1988 to celebrate its 50th anniversary, but as of September, 2003, it is out of service without a current boiler certificate. Mallard is now part of the national collection at the United Kingdom's National Railway Museum in York.