D onald Trump never did manage to build the wall on America’s southern border. Rishi Sunak may have no better luck stopping the small boats with his plan to put refugees on barges or send them to Rwanda.

But the extent to which governments will go to “defend” their borders shows just how hot a political topic migration has become across developed western nations. Nor is it just the case in the US and the UK. Both Sweden and Germany have seen the emergence of anti-immigration parties in recent years as the number of migrants has increased.

In the case of the UK, net migration – the numbers arriving minus the numbers leaving – has been positive for the past three decades. According to figures from the House of Commons library, immigration exceeded emigration by more than 100,000 in every year from 1998 to 2020. Boosted by one-off factors, such as the war in Ukraine, net migration hit a record of just over 500,000 in the year to last June.

This 30-year trend marked a break with the past. In the 1960s and 1970s, more people left Britain than arrived, and it was only in the early 1990s that net migration really started to increase. This is perhaps understandable. The 1980s and early 1990s saw mass unemployment and the UK was not the most attractive place for someone looking for work.

But the UK economy grew uninterruptedly from 1992 to 2008, and there were plenty of jobs, both of the high-paid variety in the post big bang City of London and of the low-skilled variety in hospitality and social care.

This was also the period when globalisation took off, with cheap goods from newly opened-up low-cost countries – such as China – boosting consumer purchasing power in western economies. The prosperity of the developed world was not