For the past 10 years or so, net immigration – the difference between those arriving here and those leaving – has averaged around 160,000 a year. Over that time, 1.6 million people have been added to our population. Yet as recently as 15 years ago, ministers and officials were working on the long-term assumption that net immigration would run at about 50,000 a year (as it had for the 20 years since the landmark 1971 Immigration Act) before tailing away. In 1992, the Government Actuary Department predicted that our population would stabilise at around 62 million in 2016, by which time there would be zero net immigration. Its most recent projections now envisage the population rising, if current levels of immigration continue, to 70 million by 2030; it is already growing faster that at any time since the 1960s Baby Boom.