The Tories’ ‘fake’ Labour migration numbers are hiding the demise of their own foolish policy

What should we make of the Conservatives’ claims this morning that Labour policy would mean net migration would increase by 1.2 trillion over the next five years? Oh, wait. That was their claim about Labour spending plans – in fact, their “research” suggests that migration would rise by a mere 840,000.

For those of us who work with numbers for a living, and frequently bemoan the lack of public understanding of key economic and social statistics, the way figures are abused by political parties during election campaigns is deeply depressing. (While not on the same scale as the torrent of unreliable Tory projections, Labour has made some dishonest predictions of its own – such as the claim that a Trump trade deal would cost the NHS £500m a week.)

The Conservatives’ migration numbers can easily be dismissed – in fact, they couldn’t even be bothered to get the current levels of migration right, ignoring the latest official Office for National Statistics projections. Even better, they’ve invented something called a “net visa grant”, a completely nonexistent concept that I suspect will mystify the Home Office officials who are actually in charge of granting visas.

I doubt this will have much credibility with anyone who hasn’t already bought into a completely paranoid narrative about “floods” of migrants, or the entire population of Turkey moving here if we stay in the EU. There are definitely legitimate questions about Labour policy: as part of its proposed renegotiation of the Brexit deal, would it now be prepared to accept free movement with the EU, which in turn would unlock the possibility of continued UK membership of the single market (a policy that recent polls suggest is surprisingly popular)? And, while they have rejected quotas and income thresholds, how would their policy on non-EU migration for work differ in practice from the Conservatives’ proposals? Pending their manifesto, we just don’t know.

But the Conservatives’ claim that Labour will introduce free movement with the entire world is obviously nonsensical and has already been debunked. The more interesting aspect is what it’s designed to obscure. In fact, what the Conservatives are trying to do here is to bury good news – that is, the long-overdue abandonment of David Cameron and Theresa May’s economically illiterate and politically damaging target to reduce immigration to the “tens of thousands”.

A little personal history may be in order here. When I was chief economist in the Cabinet Office in late 2010, I warned the then prime minister that he was setting himself up to fail – reducing non-EU migration very substantially would require economically damaging restrictions on skilled and student migration (absent a very prolonged recession), while EU migration would probably rise in 2014 (just before the next election) as controls were lifted on Bulgarians and Romanians.

In the end, of course, he got the worst of all worlds: May’s nasty policies, a high-profile missed target and then, in reaction to that, a doomed attempt to end free movement as part of his renegotiation of our EU membership. And we all know how that ended.

So the replacement of the target with a much vaguer commitment to “cut immigration overall” is positive. And it suggests a welcome, if belated, recognition of reality – that ending free movement will reduce EU migration. And that, given the needs of the UK economy, not to mention public services, will require a considerably more liberal policy towards skilled migration from outside the EU. We’ve already had announcements about a new “NHS visa”, as well as allowing more international students to stay on to work after they finish their studies – policies which many of us have long been arguing for.

Nor is this just about economics. It was the Cameron/May target that drove the Home Office’s focus on simply keeping people out or kicking them out, leading in turn not just to the Windrush scandal, but similar abuses and mistreatment of foreign students, as well as inhumane policies towards the families of British citizens who happened not to be rich or well-paid enough. As public opinion has shifted away from a knee-jerk negativity, we can hope that these policies too might gradually be reversed.

Related: Michael Gove is peddling the same old immigration myths | Maya Goodfellow

What would this mean for numbers overall? There’s huge uncertainty, but my modelling suggests that the overall impact might be a modest fall of about 35,000 a year, with much of the reduction in EU migration being offset by increases elsewhere. This in turn would mean that rather than exacerbating the economic damage from Brexit, as May’s restrictionist approach would, the impact would be broadly neutral – and could even be positive.

So, while it’s disappointing to see Conservative scaremongering about immigration in the headlines again, the underlying forces driving immigration policy – both economic and political – are pushing us in the right direction: away from the pointless numbers game of the last decade, and towards a more constructive debate about what an economically sensible and humane post-Brexit system might look like.

• Jonathan Portes is a senior fellow at UK in a Changing Europe