 By 1924, the prefabricated components stored at Woolwich formed 100 complete N class kits for purchase from the government.The newly created Southern Railway, which had absorbed the SECR in the 1923 "Grouping", undertook trials in early 1924 to compare the performance of its freight locomotives.Because the Ns were designed to haul both freight and passenger traffic, Maunsell, as the newly appointed Chief Mechanical Engineer of the Southern Railway, decided to compare the design with the N1, LSWR S15 and LB&SCR K classes in trials that involved hauling trains of 65 loaded wagons.