A list of the names and numbers of the SECR K and SR K1 classes of 2-6-4 tank engines that formed the River class: locomotives initially running on the South Eastern and Chatham Railway (SECR), and subsequently operated by its successor, the Southern Railway (SR) from 1923. The majority of the class consisted of 2-cylinder locomotives built to an SECR design by Richard Maunsell, but one 3-cylinder version, the K1 class, was constructed by the Southern Railway in 1925. They were given the names of various rivers by the Southern Railway in a publicity measure to advertise the area that the railway served.