Following up on my post below,  here's more from Mark Steyn:

"The central argument of [Steyn's book ] America Alone is that culture trumps economics: Even assuming there was a modest economic benefit to mass immigration, would you be willing to lose your country for it? In order to keep a handful of mills open, would you want your Yorkshire town to adopt Mirpuri practices of cousin marriage and a rate of congenital birth defects to match? Had the political class put it like that in the Sixties, there's no doubt what the answer would have been. "[Links added]

All I can say is that at least one member of the political class did put it like that—the Right Honourable Enoch Powell, member for Wolverhampton who said in 1968 that

"It almost passes belief that at this moment twenty or thirty additional immigrant children are arriving from overseas in Wolverhampton alone every week—and that means fifteen or twenty additional families of a decade or two hence. Those whom the gods wish to destroy, they first make mad. We must be mad, literally mad, as a nation to be permitting the annual inflow of some 50,000 dependants, who are for the most part the material of the future growth of the immigrant-descended population.

It is like watching a nation busily engaged in heaping up its own funeral pyre. "

Which doesn't, of course, mean that Steyn is wrong—the rest of of Britain's political class made a decision to ignore Powell's warning and condemn him for having uttered it. He predicted that, too:

"Above all, people are disposed to mistake predicting troubles for causing troubles and even for desiring troubles: "if only", they love to think, "if only people wouldn't talk about it, it probably wouldn't happen". Perhaps this habit goes back to the primitive belief that the word and the thing, the name and the object, are identical."