In today’s age when marshalling of passenger and goods trains is kept to a minimum, and eliminated in most cases, by the running of trains from A to B without division, it is often forgotten how much shunting took place on the railway. This shunting activity was either performed by the train engine or shunting engines at the major stations, junctions and marshalling yards. For these larger locations where the general code of whistles offered insufficient information to the signalmen engines used their whistle to indicate the route required via a designated code specific to a location understood by driver and signalmen alike. This publication offers a view of the intricacies involved in the operation at these major centres. The Signal Whistles book was re-issued at intervals as the North Eastern altered and expanded its major stations and junctions.