Globalisation and, central to that, immigration, saved the city. People born abroad now make up half of Londoners between 20 and 40. Immigrants form an essential part of the workforce at all skill levels — from supermarkets and sandwich shops to law firms, tech start-ups and research institutes like my own. London’s recent economic growth has been driven by immigration; without immigration it would come to a screeching halt. Immigration makes London, by far, the most productive part of the UK.