Moira Stuart tells the astonishing story of the idea of the Unknown Soldier - a powerful prism for national grief, a brilliant interplay between anonymity and universal recognition, an icon which spread across the globe. But even from the beginning the concept of the Unknown Soldier was not without its critics. Some saw it as emblematic of the callousness of states and their governments in wartime - the Unknown could be read as figure of righteous anger, of the terrible, mass anonymity of countless young men lost without trace.