This comprehensive history of these unique locomotives covers everything from performance issues to sightings, detail differences and liveries. The Type 2 Bo-Bo Diesel-Electric Classes 21 & 29 locomotives were constructed by the North British Locomotive Company in the early 1960s. Used in the Scottish region of British Railway, they ran into numerous problems and were withdrawn from service within a decade. Due in part to their short careers, these locomotives remain something of a mystery to train enthusiasts. The scant information available on them is very often riddled with misinformation. This authoritative volume corrects the record, presenting the most comprehensive and accurate account of the NBL Classes 21 & 29. Fully illustrated with photographs and detailed line drawings, this volume offers individual locomotive histories, complete technical specifications, accident and fire damage reports, storage histories, and a complete account of their disposal at both private companies and Glasgow Works.