In 1948, British Railways inherited myriad coachs from the "Big Four" companies. From the early 1950s, standardisation was imposed with, initially, the Mark 1 design, later further developed to produce the Mark 2 and Mark 3 models from the early 1960s onwards. From the mid-1970s onwards the trend has been for the locomotive-hauled stock to be gradually replaced by HSTs, used nationwide, the Intercity 225s designed for use on the electrified East Coast main line and a wide range of diesel and electric multiple units of varying sizes and specifications. Today, a conventional locomotive hauled passenger train is a comparative rarity.