The third of Colin Boocock's 'Compendium' titles provides a guide to all DMUs constructed for use in Britain and Ireland over the past 60 years. The Diesel Multiple-Unit first appeared pre-World War 2 but it was not until the introduction of the Derby Lightweight units in the early 1950s that large numbers were produced. Cleaner and more efficient than the steam services that they replaced, it was hoped that the DMU would provide the salvation of many of the countryAEs unremunerative passenger lines. Initially, their impact was dramatic but eventually even the savings produced by the DMUs proved insufficient and many of the lines for which they were constructed fell victim to the Beeching Axe. The first-generation DMUs dominated passenger traffic outside the electrified network for more than 25 years and the final examples have only just been withdrawn, some 50 years after their introduction. The second generation of BR DMUs started to appear in the mid-1980s; many were initially built with relatively no expense " such as the various Pacer Units " but by the era of Privatisation the new units had supplanted the first-generation stock on most services and since Privatisation the process has been completed. The book not only includes the DMUs history in Britain but also in Ireland. The Irish content emphasises that, in many ways, BR and CIE were facing the same problems and were adopting similar solutions, the Irish were in many respects ahead of practice in Great Britain.

Following the true 'Compendium' format, each class of DMU is profiled on one page, including a brief commentary, a table of key facts and dimensions, accompanied by a large picture of the standard version of the class, and pictures of all significant variations. The book includes c200 mono and colour illustrations.