I was lucky enough to be given a quick tour of Inverness Signalling Centre on 3 November. Above is a general view of most of the control desks which the signallers use. It's remarkable that the entire Far North and Kyle Lines are controlled from here using the RETB (Radio Electronic Token Block) system.

The signallers are in verbal communication with the train drivers each time a train comes to the end of one block (section of route) and needs to enter the next. In past times each track section had one physical 'token' which was held by the train crew and handed in or collected at the beginning/end of each single-line section. This prevented two trains at once being in the same block - essential on single-track railways to avoid head-on collisions.

In the adjoining room are racks of processing units which perform the vital task of 'interlocking' to ensure that no incorrect, and therefore dangerous, manoeuvres can take place.