This is much more than the standard locomotive photo album we've all seen. This book is targeted at the locomotive historian and/or modeller and contains many photos (perhaps more than half in colour) of specific detail features of the Class 40 type, as well as variations of those features between individual Class 40 locomotives. Grille, exhuast, bogie, boiler, buffer beam, water tank, gauges, handrails, nameplates, numbering, nose doors, headcodes, livery, ladders, and many, many, many more individual features of these locomotives are shown in photographs and explained. The book is divided into brief sections with text giving an overview of a particular feature, and then each feature is further explained by informative captions to several photos which illustrate the variations in the feature between individual locomotives, and also variations resulting from changes made to them over time. Construction details are given as are naming details for the engines which were given names. Locomotive allocations and routes are covered. Line drawings I believe to be in 4mm are supplied for the three main nose-end variations, with their corresponding side profiles. There is no drawing of the top of the locomotive, but roof features are covered sufficiently by photographs. This book is the first in a new series from Ian Allan, and I can only hope that the publisher releases further volumes in the series to cover all the major diesel classes, as this book is an indispensable reference.