LNER Class A4
The Class A4 is a class of streamlined 4-6-2 steam locomotive designed by Nigel Gresley for the London and North Eastern Railway in 1935. Their streamlined design gave them high-speed capability as well as making them instantly recognisable, and one of the class, 4468 "Mallard", holds the world record as the fastest steam locomotive. Thirty-five of the class were built to haul express passenger trains on the East Coast Main Line route from London Kings Cross via York to Newcastle, and later via Newcastle to Edinburgh, Scotland. They remained in service on the East Coast Main Line until the early 1960s when they were replaced by Deltic diesel locomotives. Several A4s saw out their remaining days until 1966 in Scotland, particularly on the Aberdeen - Glasgow express trains, for which they were used to improve the timing from 3.5 to 3 hours.
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.