Now in its second edition, this book succeeds at several levels. Historical background and basic explanation is carefully covered with the assistance of graphics, drawings and a helpful glossary of terms. Well-captioned photographs illustrate important aspects of signalling development throughout the period. There is detailed coverage of contemporary developments in the science and practice of signalling, as well as helpful reference to remaining areas of traditional signalling and to the preserved railway sector. The style is lucid and racy, and the quality of production and illustration quite superb. Highly recommended.