Nigel Gresley
Sir Herbert Nigel Gresley (19 June 1876 – 5 April 1941) was an English railway engineer. He was one of Britain's most famous steam locomotive engineers, who rose to become Chief Mechanical Engineer (CME) of the London and North Eastern Railway (LNER). He was the designer of some of the most famous steam locomotives in Britain, including the LNER Class A1 and LNER Class A4 4-6-2 Pacific engines. An A1 Pacific, "Flying Scotsman", was the first steam locomotive officially recorded over 100 mph in passenger service, and an A4, number 4468 "Mallard", still holds the record for being the fastest steam locomotive in the world (126 mph).
4-6-2
The Great Northern Railway (GNR) and the North Eastern Railway (NER) each built two Pacific types in 1922, later to become the Classes A1/A3 and A2 on the London and North Eastern Railway (LNER). Further examples of these two classes were built by the LNER after 1923.
The GNR Class A1, designed by Sir Nigel Gresley and later rebuilt into the improved Class A3, featured three cylinders and an innovative conjugated valve gear. The class eventually consisted of 79 locomotives. After initial teething problems, it proved to be an excellent design and one of them, the "Flying Scotsman", was the first British locomotive to be officially recorded as reaching .
This speed was surpassed by the streamlined LNER Class A4 of 1935, when no. 2509 "Silver Link" reached on its inaugural run in 1935. Three years later, on 3 July 1938, no. 4468 "Mallard" touched , which is still the world speed record for steam traction. 35 locomotives of the class were built by 1938.