One of my proudest achievements in government was meeting Britain’s commitment to spend 0.7 per cent of its national income on overseas development. From that fraction flowed some much bigger numbers. Eleven million more children going to school. Twenty-four million mothers and children getting the nutrition they need. Sixty million more people accessing clean water and sanitation. Millions more protected from diseases such as malaria and polio. It was a promise made to the world’s poorest...