On the eve of WWI, there were 19,245 route miles of railway in Britain. Apart from some suburban electrification in a few major city areas, this vast network was worked entirely by steam locomotives.  Each year several hundred locomotives were built while others were scrapped. The picture was therefore continually changing almost by the day, as between 1901 and 1914 a new build locomotive design or variant appeared somewhere, on average, at the rate of one every three weeks. The dramatic increase in the size of locomotives during this fairly short period was also unparalleled.  It was goods rather than passenger traffic that earned most revenue for many railways. Railway engines consumed about 13 million tons of coal annually and as the pit head price of coal steadily increased, the railways sought ways to reduce their coal consumption and thereby maintain profitability, superheating being an important innovation in this respect at this time.  This book closely examines all aspects of steam operations in this era, making use of largely overlooked published official statistics to present a detailed and fascinating picture of the time which has been described as the Golden Age of Britain's railways