The Conservative pledge to reduce net immigration to “tens of thousands” lies in tatters. Net migration is now running at over 300,000 a year, just below its previous peak under Labour in 2005. And just as there are upsides to immigration, there are also downsides – especially at these levels. First, as Ryan Bourne has explained on this site, immigration is bad for Britain’s least skilled people: “highly skilled migrants often compete with lower skilled Brits, keeping wages lower than they otherwise would be for that group.” Second, it puts pressure on public services: schools, hospitals, housing, roads, rail, infrastructure. Finally, it can cause social cohesion problems – if large numbers of people don’t speak English, for example.

All the available polling shows that most voters want less migration – though it also suggests that their desire to see a reduction is matched by cynicism about the politicians’ willingness to provide one. But many of those who don’t want less immigration want better immigration control. This one of the reasons why Bright Blue’s manifesto on the subject proposed the publication of an annual migration impact assessment, a new class of national insurance contribution to be paid by migrants, and higher visa and citizenship test fees. This was part of a mix that would see a more relaxed regime for students, tourists, asylum seekers and family members, plus a gross rather than a net target.

But whether or not you are part of the majority that wants less immigration, or part of the even larger one that wants better immigration control, you will find that the bedrock EU principle of free movement is a roadblock to both. Originally, it applied only to workers in a smaller EU, or community, of western European states. But first the Maastricht Treaty broke the link between movement and work during the 1990s, and then enlargement in 2004 swelled the number of people entitled to come here. Nigel Farage made political hay with the latest wave of those entitled to do so – entrants from Romania and Bulgaria: the number of the former last year rose fivefold.

EU migration is less than half the total – roughly 270,000 people last year compared to 290,000 from outside the EU. It is possible to imagine that the Government might meet its net migration target were Britain to experience a slump while the Eurozone boomed, or solely by imposing further restrictions on the number of students who enter from outside the EU. But this would plainly be both an unreliable and undesirable way of reducing numbers. The prospect of a booming Eurozone and bust Britain is – shall we say – a bit remote. Indeed, the new minimum wage looks as though it will be, inter alia, a magnet for further EU immigration. And no-one designing a rational migration system would begin by making it easier, say, for low-skill Slovenians to enter Britain than higher-skill Indians.

But as matters stand, Theresa May is straining to get net migration down by yet another push to reduce non-EU student numbers. (These represent over half of the non-EU immigration total.) A more reasonable course for both those who want lower immigration and better immigration control would be to control EU entry directly. A lower number of EU migrants would give policy-makers more leeway. They could aim for lower migration, either net or gross. Or they could settle for a higher rate than the lower immigration lobby would like, and trade off fewer EU migrants for more non-EU family members, asylum seekers, tourists and students – exactly as Bright Blue propose.

This was also the approach outlined in our own ConservativeHome Manifesto. It should be conceded at once that leaving the EU would not automatically guarantee lower migration. As a group of Business for Britain authors pointed out recently, EEA members, such as Norway and Iceland, have also signed up to free movement: “should the UK seek to retain the EEA’s access to the European Single Market, in all likelihood this means little substantial reform of the EU’s free movement rights for the UK,” they wrote. However, they went on to say that coming to a new arrangement with the EU that would qualify or exclude the principle of free movement would be “politically tricky, but not impossible”.

“The UK could also have access to a wider global talent pool without the uncontrolled pressures of free movement, and its immigration policy could be fairer by providing enhanced opportunities for highly skilled workers from the rest of the world to work in the UK,” they continued, suggesting a range of options including the extension of free movement rights to economically advanced nations outside Europe, or its restriction to economically-developed Western European states, or a reformed work visa regime – or a mixture of all together.

In essence, they were outlining a spectrum of options which range from aiming for more immigration to going for less. But either way, we would have more control than now: we would be exchanging a policy that has failed for one that would work. Furthermore, the policy hasn’t simply failed in the past: it is set to carry on failing unless recession comes. (David Cameron’s original lower net immigration promise – “no ifs, no buts” – has now been downgraded to an aspiration.) Even a downturn might not deliver a net reduction – and, in any event, it is perverse to rely on economic failure to deliver migration control success. In the absence of EU-wide willingness to curb free movement significantly, the only route to better immigration control is Brexit.