At the beginning of 1937, Britain was the only global power with interests in every continent and, in theory, the means to defend them. The British system was a close approximation to a world empire. Its prestige had been dented by recent events, and its wealth diminished by depression. But no other great power could match its combination of military (mainly naval) and economic strength or its latent ability to coerce its enemies. The intimidating scale of its territorial extent, including its self-governing member states and colonial possessions, made it hard to imagine the ultimate defeat of such a global leviathan. Indeed, life outside the limits of empire seemed scarcely conceivable to the sturdiest nationalist – at least as a realistic prospect in the foreseeable future. In what was still an imperial world across much of Afro-Asia, there were few free places on the map.

But empires can disintegrate with astonishing speed. The collapse of the Soviet empire at the end of the 1980s took almost everyone by surprise, not least the school who had proclaimed the imminent decline of American power. In the British case, the change was almost as sudden. By the middle of 1942, Britain, the imperial centre, was effectively bankrupt and dependent upon American aid. With the fall of Singapore in February, the invasion of Burma, and the German advance into Egypt (the battle of Alamein was fought scarcely 100 miles from Cairo), the British system looked set to collapse.