First introduced in the early 1950s, the diesel multiple-unit represented an attempt to produce a vehicle that would replace steam traction on the countrys branch lines and secondary routes at a time when the railway industry was in desperate need of a cheaper alternative to steam in order to improve the finances of these increasingly unremunerative lines. Initially introduced in areas such as the north west of England, the West Riding of Yorkshire and East Anglia, the arrival of the new and much cleaner Diesel Multiple Units (DMUs) undoubtedly helped to stem both the loss of passenger traffic and improve, at least briefly, the economics of the lines over which they operated. Between the early 1950s and the start of the following decade, several thousand of these units were produced by a variety of manufacturers for service nationwide. However, despite the cost savings that these units represented, the financial position of the railways continued to deteriorate with the result that many of the lines for which they were designed were closed in the wake of the Beeching Report. Following refurbishment from the early 1970s onwards, many first generation DMUs were to survive in service until the late 1980s or early 1990s. Indeed a handful can still be found in operation almost 50 years after the first of the type entered service. Although most were scrapped after withdrawal, a significant number of these vehicles have been preserved on the nations heritage railways. In 2005 OPC published Hugh Longworths British Railway Steam Locomotives 1948-1968. This definitive listing of every steam locomotive operated by BR between 1948 and 1968 was one of the most successful railway titles of 2005 and was quickly reprinted on three occasions. Having examined the steam locomotive fleet in detail, Hugh Longworth now turns his attention to all of the first generation DMUs constructed. As with the earlier book, each type is covered in detail with information given about construction, technical specifications, entry into service, withdrawal and its fate. Alongside the detailed tabular material the book also includes some 125 mono illustrations recording the great variety of DMU constructed as part of the programme. Comprehensive in its coverage, this new addition to the OPC list will be sought after by all those modellers, preservationists and historians seeking a detailed reference work on the history of these first generation DMUs.