'Keep Calm and Carry On' has become one of the most recognisable slogans of the twenty-first century. But where is it from and why has it resonated so strongly with the modern British public? This book reveals the truth behind the now infamous poster, tracing its origins to the Second World War, when it was created to allay public panic in the event of a German invasion. Of course this feared invasion never happened, and the poster would have been resigned to the dusty shelves of history were it not for a chance discovery by the owners of Barter Books in 2001. Later seized upon as an encouragement in the economic crisis, 'Keep Calm' went on to become arguably the most successful meme in history. This book tells the story of that phenomenon, including colourful posters and archive photographs throughout.