Britain's population will swell to 69 million by 2050, according to a United Nations prediction.
Immigration will be responsible for around three-quarters of the 9 million increase – the equivalent of 150,000 new arrivals a year.
Is that all? In 2005, 474,000 immigrants entered the UK.
The UN’s population division says the changes will be part of a global upheaval without parallel in human history.
The world’s population will grow by 2.5billion over the next four decades to reach about 9.2billion by 2050.
Almost all the increase – the equivalent of the entire global population in 1950 – will happen in Africa, Asia and the Middle East.
Tens of millions of people from these areas will migrate to Europe and America, with 2.2million new arrivals each year across the developed world.
Yet the native populations of most developed countries will either stagnate or decline, the UN predicts.
Nor will all Western countries be as much of a magnet for migrants as the UK, the report says.
The prediction will increase concern that Britain is taking a disproportionately large number of migrants, attracted by the Government’s "open door" policies.
Migrants are also seeking to benefit from the availability of jobs here, as well as a relatively generous benefits system.
All have been significant factors in migrants adding around 1.5m to the UK population since Labour came to power in 1997.
Of course, at the beginning of this post I mentioned that the population of developed countries would decline. But, with this rate of immigration, will the UK still be a developed country in 2050? Our infrastructure will surely be put under immense pressure by all these extra people. And there's the simple question whether a country that imports millions and millions of ill-educated and culturally backward people (as most of these immigrants are and will be) can avoid being sucked down into a general intellectual and cultural malaise itself? I somehow doubt it.