The British Dream: Successes and Failures of Post-War Immigration. By David Goodhart. Atlantic; 381 pages; £20. Buy from Amazon.co.uk

DAVID GOODHART dislikes immigration. He thinks Britain has made a colossal mistake by being so open to foreigners over the years. The efforts of the current Conservative-led coalition government to drastically reduce net immigration do not, in his view, go far enough. He not only disapproves of ghettoes, where immigrants subsist on welfare and fail to integrate into British society. He also dislikes places like London’s financial district and Silicon Valley, with their highly productive, English-speaking immigrants. He can just about tolerate foreign players in the English Premier League, but that is about it.

He has many reasons. New arrivals make life harder for native workers, asserts Mr Goodhart, who runs Demos, a centre-left think-tank. They compete for public services. Their ghettoes are an affront to common decency. By making Britain more diverse, they have reduced fellow feeling. When a country has lots of immigrants, its residents turn against the welfare state: people are less inclined to contribute money to a system that seems to benefit people who do not look like them. The churn of new arrivals also makes it harder to integrate previous generations of immigrants.

So runs Mr Goodhart’s argument. His position is not original, although he has made the argument about immigration undermining the welfare state his own. Nearly all British people agree with him that there is far too much immigration. But “The British Dream” is not consistently polemical. Wrapped in an insistent, occasionally intemperate argument about the malign effects of immigration is something much more interesting: an analysis of how immigrants have fared in Britain, and how they have changed the country. This bit of the book (roughly the middle 250 pages) is fairly unbiased, well-researched and shrewd—so much so that it makes Mr Goodhart’s conclusions seem rather odd.

The immigrant Britain described in this book is hugely diverse—almost as much so as British society itself. There are, the author explains, enormous differences between west African and east African immigrants, between Pakistanis from the Mirpur Valley and Pakistanis from Lahore. Afro-Caribbean women fare much better than Afro-Caribbean men. Some groups, like the Indians kicked out of Uganda by Idi Amin, have succeeded spectacularly. Others, like Somalis, are in desperate shape. Some, like Indians, are economically integrated but still tend to marry among themselves; for others, like Afro-Caribbeans, the reverse is true. And everybody is becoming more mixed.

Mr Goodhart tries to focus on immigrant groups that have not integrated much, and on places where segregation is sharpest. He returns again and again to the Mirpuris who have settled in Bradford—an exceptionally isolated and troubled bunch. But his gaze often wanders, to places with happier and more interesting stories. Even when he focuses on the trouble-spots, he is honest enough to admit that towns like Bradford are becoming less segregated (at least in mathematical terms); that imams are more likely to speak English these days; and that young British Pakistanis are much more likely to be in education than are whites.

Honest admissions of tricky evidence repeatedly undermine the argument. In a long attack on obsessives who see racism everywhere, for example, Mr Goodhart mentions a startling statistic. Send out CVs with ethnic-minority-sounding names, and the response from employers is barely half as good as the response to CVs with white-sounding names.

The result is a book that does not really accomplish what it sets out to achieve. Mr Goodhart does not convince the reader—at times he does not even appear to convince himself—that immigration is such a terrible thing. He has even moderated his theory that immigration must be bad for the welfare state, which caused a stir in Britain a decade ago: he now thinks welfare can persist even in an immigrant society if it is made more contributory. The book is good sociology, and, as a result, poor polemic. “The British Dream” fails. But it would have been a much worse book if it had succeeded.