High Quality Content by WIKIPEDIA articles! The LSWR S15 class was a British 2-cylinder 4-6-0 freight steam locomotive designed by Robert W. Urie, based on his H15 class and N15 class locomotives. The class had a complex build history, spanning several years of construction from 1920 to 1936. The first examples were constructed for the London and South Western Railway (LSWR), where they hauled freight trains to the south coast ports and further west to Exeter, as well as occasional passenger work in conjunction with their larger-wheeled N15 class counterparts.