Book excerpt: For over 150 years Britain's railways have relied on a system of semaphore signalling, but by 2020, all semaphore signals and lineside signal boxes will be gone. A Contemporary Perspective on GWR Signalling provides a unique record of the last operational mechanical signalling and infrastructure on Britain's railway network, as it applied to the former Great Western Railway (and lines owned jointly with other companies). It also includes a comprehensive explanation of what mechanical signalling is and how it works. Beautifully illustrated with over 400 contemporary images and with detailed information from a 2003-2014 survery, this is an essential resource for anyone with an interest in the traditional signalling systems of railways in Britain. The book covers: lineside signalling equipment - semaphore signals, brackets and gantries, and other variations; ways of working, from Absolute Block to Track Circuit Block (TCB); detailed coverage of the signal boxes and infrastructure on Network Rail, including routes through Shrewsbury, Hereford, Worcester, Cornwall, Chester and North Warwickshire; and diagrams of the major routes.