Along with the nuclear deterrence, shipping routes form the existential core of our national security. These routes – vital in world wars against Napoleon, the Kaiser and Hitler – depended on a powerful, globally deployed navy. The Admiralty built, maintained, crewed and directed the navy in war and peace, stood up to the Treasury and co-ordinated with the War Office on strategy. After 1964, British strategy was no longer shaped by the realities of geography and oceanic dependence. In this regard, the Nato defence spending goal of 3 per cent of GDP is an unhelpful incentive.