With the first of the future Class 31 design emerging over half a century ago in 1957, these adaptable locomotives have proved themselves to be amongst the most successful and long-lived of all Modernisation Plan diesels. Between 1957 and 1962 more than 250 locomotives were constructed, and despite massive withdrawals from the mid-1990s onwards, a handful still remains in service with others now in preservation. Initially intended for use on both passenger and freight services on the Eastern Region, the type was later to see service on the Western Region replacing the diesel-hydraulics, and on inter-regional services such as those from Birmingham to Norwich.Privatisation of the railway industry saw the bulk of the survivors pass to EWS ownership, but several others are now owned by charter companies such as FM Rail and by Network Rail itself in a bright yellow livery. This informative new book concentrates primarily on the era after 1980, and is designed to complement the original OPC volume "Power of the 31s". The well-researched text explores the history and development of the 31s, and is supplemented by a vivid collection of over 250 mono and colour images of the class in various locations around the country. This impressive collection of images focuses in particular upon the many livery variations to have been carried by the locomotives since their introduction. These will be of great interest to modellers of the type as well as to diesel enthusiasts around the country.