The last time the calendar saw out the decade of the teens and ushered in that of the 20s – fully one hundred years ago – the world was a very different place. There is no experience in our recent lifetimes to compare to the devastation of the First World War, an event that brought down empires and left widespread misery, resentment and loss of wealth in its wake. The early years of the 1920s were a time when nations tried to pick up the pieces and rebuild their broken societies. But rebuild how? What was the right formula for ensuring that the calamity of 1914-18 would not be repeated?