Although the first diesel multiple-units (DMUs) first appeared in the 1930s and the first of the Derby lightweight units shortly after Nationalisation, it was the Modernisation Plan of 1955 that resulted in the mass introduction of DMUs on to the British Railways network. The DMU was seen as essential to the future of secondary and branch lines, offering better quality rolling stock than traditionally provided, with lower operating costs. Indeed, the launch of DMU services on many lines did result in a temporary improvement in the performance of the affected routes and by the early 1960s several thousand first-generation DMUs were to be seen in operation over much of the network. However, the Beeching Report was to cast a shadow over the next decade and few new units were introduced between the early 1960s and the late 1970s when the urgent need to replace the increasingly aged first generation units became apparent. However, almost 50 years after the first of the Modernisation Plan units entered service the last of the type remain operational.In the second of Ian Allan Publishing's new 'British Railway Pictorial' series, Kevin Robertson pays tribute to this essential workhorse of the modern railway era. With the aid of over 175 mono illustrations, he examines the genesis of the type, the great variety of examples constructed and the range of services operated. For a whole generation of railway enthusiasts, the DMU was the unsung hero of the railway industry. Whilst it may have lacked the glamour of steam, it provided a reliable standard of service for more than four decades. Now that the majority have been withdrawn, the once familiar sights are no more. This new pictorial portrait, paying tribute to the DMU, will be of interest to the modeller, historian and preservationist alike.