The LSWR 415 class is a 4-4-2T steam tank locomotive, with the trailing wheels forming the basis of its "Radial Tank" moniker. It was designed by William Adams and introduced in 1882 for service on the London and South Western Railway (LSWR).

Originally rostered for suburban traffic, the class was soon displaced to the countryside by Dugald Drummond's M7 class. Most of the class was scrapped around the end of the First World War, and further decreases meant that all of them were due to be withdrawn by 1929. However, the class was noted for its long service on the Lyme Regis branch line, and three members of this long obsolete class were utilised on this duty until 1962, when suitable replacements became available. One has survived