Two-part documentary telling the remarkable story of a band of visionaries who rescued some of the little narrow gauge railways that once served Britain's industries. These small railways and the steam engines that ran on them were once the driving force of Britain's mines, quarries, factories and docks. Then, as they disappeared after 1945, volunteers set to work to bring the lines and the steam engines back to life and started a movement which spread throughout the world. Their home movies tell the story of how they helped millions reconnect with a past they thought had gone forever.