This book is one in the Pen & Sword Transport History imprint in the Locomotive Portfolio series and covers the family of two-cylinder 4-6-0s designed and built by the Chief Mechanical Engineers of the London & South Western and Southern Railways between 1914 and 1936, which survived well into the era of British Railways. The N15 King Arthur class of express passenger engines were the mainstay of the Southern Railway s passenger business between the two world wars, but both Robert Urie and Richard Maunsell built mixed traffic and freight locomotives of a similar ilk forming a King Arthur family of locomotives for all purposes that were simple, robust and long lived. This book describes the conception, design and construction of the N15, H15 and S15 classes and the N15X rebuilds of the LB&SCR Baltic Tanks and their operation in traffic before and after the Second World War, until the withdrawal of the last Maunsell 4-6-0 in 1965. The book includes extensive personal recollections of the author, who both saw and travelled on hundreds of trains hauled by many of these engines in the 1950s and 60s, and gives a brief summary of those that have been preserved on Britain s heritage railways. The book is copiously illustrated with over 200 black and white and colour illustrations.