London and North Eastern Railway locomotive numbered 4468 Mallard is a Class A4 4-6-2 Pacific steam locomotive built at Doncaster, England in 1938. It is historically significant as the holder of the world speed record for steam locomotives at 126 mph (203 km/h).

The A4 class was designed by Sir Nigel Gresley to power high-speed streamlined trains. The wind-tunnel-tested, aerodynamic body and high power allowed the class to reach speeds of over 100 miles per hour (160 km/h), although in everyday service it rarely attained this speed.

The 'Mallard' was fitted with twelve boilers during its 25-year career. These boilers were: 9024 (from construction), 8959 (from 4496 Golden Shuttle, 13 June 1942), 8907 (from 2511 Silver King, 1 August 1946), 8948 (from 31 Golden Plover, Walter K Whigham, 10 January 1951), 29301 (from 60019 Bittern, 4 July 1952), 29315 (from 60014 Silver Link, 23 April 1954), 29328 (new-build boiler, 7 June 1957), 29308 (from 60008 Dwight D. Eisenhower, 27 August 1958), 29310 (from 60009 Union of South Africa, 9 March 1960) and 27965 (from 60009 Union of South Africa, 10 August 1961).

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