Wikipedia:Today's featured article/May 18, 2016

The SECR K class was a type of tank locomotive designed in 1914 by Richard Maunsell for express passenger duties on the South Eastern and Chatham Railway (SECR). The Southern Railway (SR) K1 class was a three-cylinder variant of the K class, designed in 1925 to suit a narrower loading gauge. They were among the first non-Great Western Railway (GWR) types to use and improve upon the basic design principles of power and standardisation established by George Jackson Churchward, the GWR's chief mechanical engineer. The locomotives were based on the GWR 4300 class, improved by the Midland Railway's ideals of simplicity and ease of maintenance. The K class was designed to be mechanically similar to the SECR N class mixed-traffic locomotives. The class was the earliest large-scale use of the 2-6-4 wheel arrangement in Britain. Production began towards the end of the First World War, and the prototype rolled out of Ashford Works three years after design work was completed due to wartime production constraints. They were rebuilt as the SR U class and SR U1 class 2-6-0s following a railway accident at Sevenoaks, Kent, in 1927. One K class rebuild (No. 31806) is preserved on the Swanage Railway in Dorset.