Summary: The news this week is that net migration into the UK during 2010 was up 20% on the previous year, despite the Conservative-led government pledging to reduce net migration to "tens of thousands". While their objective looks as impossible to achieve as ever, some of the hysteria surrounding the latest figures is unnecessary.
What does the chart show? The blue and red line show immigration and emigration respectively, in thousands of people over the previous 12 months. The black dotted line shows the difference between the two, or net migration; this is the growth in the population over the past year attributable to migration, rather than births and deaths.
Why is the chart interesting? The chart shows that total immigration hasn't changed much since 2004, when it grew by about 100,000 people per year. Most of the changes in net migration since then have come about as a result of shifts in emigration, which reached a peak in 2008 and has fallen steadily since. In fact, the 20% rise in net migration between 2009 and 2010 is only about 1/5 due to a rise in immigration, and 4/5 due to a fall in emigration. When the government set a target of less than 100,000 net migrants per year, one doesn't imagine they meant they would encourage more Britons to leave the country.
Within the steady immigration numbers, though, there is a hidden shift. In the wake of the recession in 2008, the number of immigrants arriving for work purposes dropped dramatically, while the number of immigrants arriving to study rose, so that now students make up the biggest proportion of immigrants arriving in the UK. The important difference between the two groups is that students are only likely to stay for between 1 and 4 years, depending on their course, and are extremely limited in what jobs they can take while they are in the country. In other words, it is the kind of temporary immigration that most people don't mind.