LNER Gresley Classes A1 and A3

The Gresley Classes A1 and A3 were 4-6-2 Pacific steam locomotives that Nigel Gresley designed for passenger service on the Great Northern Railway, and they became the standard main-line express design of the London and North Eastern Railway after the 1923 grouping. The first two, 1470 Great Northern and 1471 Sir Frederick Banbury, appeared in 1922 and were modelled on American practice, with a large boiler and wide firebox and Gresley's three-cylinder layout. The LNER built 51 A1s between 1923 and 1925, twenty by the North British Locomotive Company and the rest at Doncaster Works. The change from A1 to A3 recorded a higher pressure boiler with more superheating, and almost all A1s were rebuilt that way. Most were named after racehorses; the class included 4472 Flying Scotsman, the only member to survive and now part of the National Collection.