 A new classification system was devised in which, for example, all Brush Type 4 locomotives were now called Class 47 and all had numbers beginning 47xxx.The InterCity 125 was planned as a stop gap measure, meant to fill until electrification was spread across all main lines and the Advanced Passenger Train (APT) was in service.Research had begun for the tilting train but it was not possible to predict when the APT would enter service.