This book covers the design, construction, operation and performance of Sir William Stanier's masterpiece, the Princess Coronation pacific locomotives, better known as the 'Duchesses'. Included are pen portraits of the LMS engineers, a chapter on the express locomotives of the early LMS period that preceded their introduction and the internal rivalries and politics that Stanier was brought in to resolve. Chapters and photographs cover the streamline era, the war years and aftermath, the early years of nationalisation including the 1948 locomotive exchanges and the recovery of performance in the mid-1950s. The author includes some of his own experiences and photographs. The book includes 200 photographs including a few in color from the LMS era, and an appendix with weight diagrams, and statistics of the locomotive construction and withdrawal, names, liveries, allocations and mileages.