Four years ago, the Home Office proposed that skilled migrants should only be allowed to stay in the UK for six years. After that, unless they were earning more than £35,000, they would have to leave – regardless of how well they were doing in their job. At the time, I and other economists warned that the policy could almost have been designed to deter the migrants the UK most needs; and, for those who do come, to expel many of those we would most like to remain.

New immigration rules will cost the NHS millions, warns nursing union Read more

So it is depressing, but in no way surprising, to read that these rules, which are due to come into effect in April next year, will mean that up to 30,000 nurses may have to leave the UK over the next five years, at a substantial cost to the NHS. As the chief executive of the Royal College of Nursing, Dr Peter Carter, put it: “The UK will be sending away nurses who have contributed to the health service for six years. Losing their skills and knowledge and then having to start the cycle again and recruit to replace them is completely illogical.”

The government justifies this policy with reference to its target to reduce net migration to the tens of thousands. But it’s far from clear that kicking out experienced foreign nurses will magically result in an increase in the number of native British ones. More likely, the NHS – and the expensive agencies that are increasingly filling the gaps – will simply recruit more nurses from within the EU or if necessary outside it. The same goes for other skilled medical staff – more than a third of doctors were trained abroad, and with a growing shortage of GPs, it is difficult to see this figure falling sharply.

Some argue that it is irresponsible for a developed country like the UK to import health workers from countries where they may be needed more. But in fact, this is hugely exaggerated – the most important countries of origin for skilled NHS staff, such as the Philippines and India, actually welcome and even encourage emigration. Even in sub-Saharan Africa, where there are genuine shortages, the countries with the worst-performing health sectors are generally those with the lowest levels of emigration of health professionals – so emigration is clearly not the main problem.

This is far from the best of times for the NHS, with funding already extremely tight and likely to become even more so

Is not the long-term answer to train more British nurses? Of course, the NHS can and should train more staff. But at the best of times any organisation with more than a million employees, with hundreds of different skills and specialisms, will struggle to match demand with supply. And this is far from the best of times for the NHS, with funding already extremely tight and likely to become even more so.

So there is a clear choice, not just for the government but for society as a whole. We value the NHS; we know that it relies on migration for a large proportion of its staff; and we know that demands on the service are likely to increase faster than its funding for the foreseeable future. Is our priority really to reduce immigration, even if that means putting further pressure on an already stressed NHS? Or would we rather continue to have skilled migrants working in our hospitals and accept that this means somewhat higher levels of immigration? We can decide we want fewer immigrants at almost any cost. Or we can have a properly staffed NHS. We can’t have both.

And while the NHS is probably the most obvious example of the damage done by the government’s approach to skilled migration, the impact will be felt across the economy as a whole. The government view – that we should only allow people to work here temporarily, to fill certain narrowly defined areas of “skills shortages”, and then only until we can “train our own people” – is completely at odds with the market-oriented approach espoused by UK governments in other economic policy areas for the past three decades. It assumes that bureaucrats in Whitehall can, with the help of “expert economic advice”, determine what skilled workers the country needs, in what sectors, now and in the future; and exactly who, at what salaries, companies should be able to employ.

I have nothing against either Whitehall bureaucrats or economists. But we don’t ask them to decide now how many cars the UK should produce in five years’ time, or how many insurance companies we will need in 10 years and what products they should offer. Any attempt to do so would rightly be ridiculed as a throwback to the worst excesses of central planning. So why are we trying to do the same for people, whether they are nurses in our hospitals, or scientists in our universities?