The steam locomotive was one of history's greatest inventions, and it revolutionised transport throughout the world. Huge numbers of individual steam locomotives were produced during the two centuries of its history, and in this series we see some of the greatest of them all - those built for the great original railway companies but which eventually went on to form the national British Railways. The Great Western Railway lived up to its name and was in the forefront of steam locomotive development throughout the first half of the 20th Century. It's legendary engineer, George Jackson Churchward, laid the foundations of the massive fleet of locomotives which his successors, Collett and Hawkesworth, built at the famous Swindon Works in Wiltshire. In this programme we see examples of the very many classes which pulled the trains of the GWR and its successors - from the humble Pannier tanks which did the shunting and local passenger trains, through the various freight classes to the glamorous named locomotives which hauled the express passenger trains -the much-loved "Castles" and "Kings". All live up to the title of "Great British Steam".