The Western Region (WR) diesel-hydraulics were in service with British Railways for less than 20 years and were controversial throughout that time, both within BR management and the wider media. This book follows the fleet year by year from the optimism of the late 1950s and early 1960s through middle age to their final demise in 1977. In 1959 Western Region management took a different stance from the rest of the network in its pursuance of diesel-hydraulic traction as opposed to diesel-electric more widely favoured elsewhere. Perhaps the decision grew from the tendency of the WR management to try to keep the old independent spirit of the old Great Western Railway alive, but whatever the real reason they pressed ahead and put forward a rational and scientific case for the policy based on work done in Germany to develop hydraulic transmissions that were both well-established and successful. The Western Region's hydraulic fleet included the 'Warships', the NBL Type 2 D6300s, the 'Hymeks', the 'Westerns' and lastly the D9500s. This new book covers all the types in detail with an outstanding selection of photographs to illustrate the range and variety of diesel-hydraulics that saw service across the Western Region. Informative, extended captions give a great depth of detail to the photographs, making this an invaluable portrait and work of reference. It is now more than 30 years since the last of the Western Region's diesel-hydraulic classes was withdrawn from service and those examples that remain in preservation have been in private ownership for many more years than they saw service on the main line. Despite this, there remains a continuing interest in the types and this new book will find a ready audience.