Philippe Legrain

The government famously forecast a trickle, opponents (less memorably) a flood, yet recent years have instead seen a steady stream of Polish plumbers, builders and other handy migrants. They have helped fuel Britain’s recent boom, providing the manpower to build new housing and do up old, making home improvements affordable for the less well-off, and keeping many a shopkeeper in clover.

Thank goodness the government got its figures wrong back in 2004: where would Britain be without its reliable, hard-working Poles?

We may soon find out. As The Times reveals today, the tide is turning: the Poles are increasingly going home. This leaves officials with egg on their face – again.

So much for the ONS projection, extrapolating decades ahead from a few untypical years of high migration, that Britain’s population would rise inexorably to 100 million and beyond: the equivalent, after Chelsea won the Premiership twice in a row, of assuming that they would do so indefinitely, until Manchester United stole their crown. So much for the swivel-eyed men at MigrationWatch who warn darkly that Britain is being overrun.

So much for the geniuses at the Home Office whose whizzy new skills-based points system for vetting migrants’ entry into Britain – being phased in from March – assumes that Poles will continue to do the dirty jobs and slams the door on non-EU migrants. Their half-baked system – which involves a committee of wise men trying to second-guess where future job shortages might occur – was meant to restore confidence in the government’s handling of the immigration system; instead, it is likely to exacerbate shortages, cause gluts and turn away potential Barack Obamas.

So much too for the fear, as the credit crunch bites, the housing bubble deflates and the economy loses its fizz, that the Poles would end up swelling the dole queues. With the Polish economy looking perkier while Britain’s droops and the flaccid pound devalues wages here, Poles want to go home – which sought not to astonish critics of immigration who place such importance on roots and nation.

This about-turn highlights how migration in the age of Ryanair and open borders has changed since the days when migrants arrived on steamships from the dying Empire. Most Poles are like the British brickies in Auf, Wiedersehen Pet who went to work in Germany in the 1980s: they came for better-paid jobs, not to settle. Some, like the Polish doctor featured on Newsnight who spends alternate weekends in Scotland providing the out-of-hours care that British GPs neglect, are international commuters – just like the bankers who jet between London and New York, or the Brits who commute from France. Many are young people wanting to learn English and experience life abroad, like the British working holidaymakers who flock to Australia for a year or two. Because the churn of migrants is so high, and the government counts the cumulative total of job applicants rather than those coming and going, Polish migration seemed like a deluge, when it is actually an ebb and flow.

This more fluid labour market greases the wheels of the economy, helping it speed ahead without sparking inflation and keeping mortgage rates down. And now the economy is heading south, the Poles’ departure will cushion the blow: unemployment will rise less than in previous downturns, making the recession shorter and shallower than otherwise.

In our globalising world where opportunities no longer stop at national borders and the economy is in perpetual flux, the need for a flexible, flying workforce has never been greater. If Britain had to rely solely on London builders, the 2012 Olympics would never be finished on time. So instead of urging people to get on their bike to look for a job, ministers should be encouraging them to hop on a plane.

Yet this new mobility is unsettling for politicians and many voters. Their mindsets are stuck in a bygone era where people generally stayed put, those who moved did so for good, and ossified state bureaucracies relied on the world standing still.

Our attitudes and institutions need to adapt. The government needs to learn to cope with a large, transitory foreign population on British soil – a task the private sector, which accommodates 30 million foreign visitors a year, manages fine. While better planning based on more accurate statistics would certainly help the NHS, above all it needs to become more responsive to local people’s changing needs: whether it is for Polish interpreters or patients’ desire to choose who treats them when and where.

Unlike the Poles, this newly mobile world is here to stay.