On 18th April, 1947, British forces set off the largest non-nuclear explosion in history. The target was a small island in the North Sea, thirty miles off the German coast, which for generations had stood as a symbol of Anglo-German conflict - Heligoland. Jan Rueger is Professor of History as Birkbeck, University of London. His latest book 'Heligoland: Britain, Germany, and the Struggle for the North Sea' is a microhistory of the Anglo-German relationship as it unfolded from the Napoleonic Wars to the Cold War. It takes the North Sea island of Heligoland as a prism through which to view rivalry, conflict and, eventually, reconciliation between the two nations.