The SECR K class was a type of 2-6-4 tank locomotive designed in 1914 by Richard Maunsell for express passenger duties on the South Eastern and Chatham Railway (SECR), which operated between London and south-east England. 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 GWR Chief Mechanical Engineer (CME) George Jackson Churchward. The locomotives were based on the GWR 4300 class, improved by the Midland Railway's ideals of simplicity and ease of maintenance.Scott-Morgan (2002), p. 18
