With the heavy emphasis on electrification for the London suburban area and the Brighton mainline, there was little need for new steam locomotive designs. The main steam tasks were boat trains (Dover, Folkestone and Newhaven), West of England, Kent services and freight. When designing steam locomotives, the designers had some interesting constraints that dictated where the locomotive could be used. Due to the hangover from SE&CR days, most of the lines in Kent were of fairly light construction and would not take the weight of a modern express locomotive until well into the 1930s. Hence the extensive rebuilding (and new construction) of 4-4-0 designs at a time when other lines were busily building Pacifics or heavy 4-6-0s.