Food policy across much of the world is changing. But not in Britain. That may be a costly mistake as the prices of essentials rise because of the climate emergency, geopolitical tensions and the fragility of just-in-time supply chains. Many capitals are now reviving their strategic food reserves. European nations such as Sweden, Finland, Norway and Germany are rebuilding stocks dismantled after the cold war. Climate shocks have led to Egypt and Bangladesh boosting similar programmes. Countries such as Brazil and Indonesia – sensitive to the food needs of their…