It is barely a week since Barack Obama broke the political mould on immigration by demonstrating that it is possible to do the morally right thing – to rise above narrow partisan advantage and still be an elected politician.

In his immigration speech, the US president justified his executive orders providing protection to 5 million undocumented migrants facing deportation so they could come out of the shadows by telling Americans that deporting millions was simply “not who we are”.

David Cameron’s dispiriting rhetoric on immigration is about as far removed as it is possible to be from Obama’s compassionate reminder that America was built on immigration and will continue to thrive on immigration.

Cameron’s latest contribution is simply accelerating a race to the bottom between the three main parties over how swiftly they are prepared to push for the removal of the welfare safety net from a marginal number of low-paid and jobless European migrants in Britain.

With his arbitrary net immigration target now left in tatters, Cameron, like Obama, could have risen to the occasion and tried to change the entire political tone of the debate.

Instead he continued to allow those populist propagandists, Ukip, to frame the debate in terms of narrow party advantage rather than what is good for Britain. It is hardly surprising that the Conservatives, after spending years in opposition claiming loudly that immigration had got out of control, now face the same accusation themselves.

But the truth about immigration in Britain is that it is not out of control in the way Ukip claims. Britain does not have an open door.

Cameron had to reach back to the Ugandan Asians in the 1970s to celebrate Britain’s role in providing a safe haven – he could hardly celebrate it today, when only a few thousand Syrian refugees have been allowed in. What is rarely mentioned now is that it is at least 10 years since any legal route for unskilled migrants from outside Europe was firmly shut down. The continuing shambles of the UK immigration system may make it hard to believe, but Britain already has a system of managed immigration largely based on the contribution that those allowed to come can make, whether to work or study.

For the real truth about immigration is that Britain is currently in the middle of a major jobs boom. More than 690,000 more people are in work in Britain than 12 months ago; two-thirds of those people are British and only a third are foreign nationals.

Boris Johnson told his audience in Singapore on Friday that Britain was the America of Europe. It is, as Cameron pointed out, “the jobs factory of Europe”, but as he failed to point out, it is the fact that Britain is open for business and open for skilled immigration that has fuelled that economic growth. One fact unnoticed in the recent controversial University College London study showing recent European migrants have contributed £20bn more to the British economy than they have taken out was the statistic that 63% of recent EU arrivals have a university degree.

The last 10 years have seen net immigration levels above 200,000 every year, and it is no coincidence that, as a result, Britain pulled out of recession long before the eurozone. But it will not last. As every economist knows, boom will eventually turn to bust and no politician wants to accelerate that process. For decades in the 1960s and 1970s Britain had net emigration – nobody wanted to come and work in the “sick man of Europe”.

No wonder George Osborne is reported to be among those who stopped Cameron announcing a Canute-style “emergency brake” on immigration, for it would also halt Britain’s relative economic recovery.

The dispiriting thing about Cameron’s speech is that it will frame the terms of the debate between now and next May’s election. His choice of the West Midlands to make it revives memories of the 1964 campaign in Smethwick, when the Tory Peter Griffiths was elected on the slogan “if you want a nigger for a neighbour, vote Labour”.

Griffiths was treated as a political pariah by both Labour and Tories on his arrival at Westminster. But that nasty tone is returning to British politics. Home Office “go home” vans touring areas with high immigration and Ukip candidates flirting with the language of repatriation have ensured a return to the language of 50 years ago.

It is all so far from Obama’s universal message that “We are and always will be a nation of immigrants”.