Book excerpt: Despite modern appearances, colour light signalling has been around since the 1920s and is just as full of subtle details and variations as 'traditional' semaphore signalling. The inclusion of a working signalling system within a model railway layout is technically challenging but adds realism and 'wow' factor. This new book contains a brief history of the development and deployment of colour light signalling in the UK; a basic explanation of how track design influences signalling design; an overview of the different types of point motor and, finally, descriptions of the different components that make up a signalling system and how these components are used and controlled. It is an extensive guide to developing and adding realistic colour light signalling to a model railway layout.