From 1958 onwards, vast numbers of diesel locomotives were constructed, both by BR's own workshops and by a growing number of outside contractors, to replace steam. Whilst some of the new diesel designs proved to be successful, others were not, and some failed to outlast the steam locomotives that they were introduced to replace. This colour album illustrates those early years of modern traction when many locos were being finished in an attractive green livery. Looking back at those early years of diesel motive power, the Western Region's use of hydraulic, instead of electric transmission can be seen as a mistake but so too were the designs of the Metropolitan-Vickers Co-Bo and the Clayton Bo-Bo classes. Excluding pioneering prototypes, all of the major first generation locomotive types are featured here together with a number of early DMUs and diesel shunters, providing the reader with a colourful contrast to the grime and matt black of the ageing steam fleet.