The Ahmadiyya story in Britain demonstrates what went wrong and right with immigration after the war. Newspaper clippings of the opening of the Fazl mosque show a local crowd who came to celebrate and gawp at the curiosity; they're smiling, curious, and entirely white. Although the BBC constantly tells us that Britain has always been a nation of immigrants, the demographic change of recent years has been remarkable. Under New Labour gross immigration peaked at more than 600,000 a year, and migrants from the Blair/Brown years account for 8 per cent of England's population. Most of them are settled.

DNA research by geneticists such as Bryan Sykes and Stephen Oppenheimer suggests that the Anglo-Saxons account for about 5.5 per cent of English DNA, the Vikings a slightly smaller figure and the Normans probably around 2 per cent at most. So postwar immigration has made a greater impact on English DNA than all the migrations from the building of Stonehenge to the Great War.

Yet England has had waves of immigrants, most, like the Ahmadiyya, small groups of persecuted minorities. The most famous are the Huguenots, who settled in places like Wandsworth in south-west London, also the first home of the Ahmadiyya; Wandsworth's coat of arms includes teardrops representing the sadness of the French Protestants at leaving their homeland. They also settled in Spitalfields, in east London, perhaps the only part of England that really does have a long history of migration and which to the diversity industry has become something of a modern-day Walsingham.

Spitalfields would also be settled by another persecuted minority — Russian Jews who fled the tsar from the 1880s onwards. Because both of these groups did well in Britain, and well for Britain, it has become easy to see it all as part of a narrative of one great nation of immigrants, but there are many differences. One is sheer numbers — Huguenots and Jews each accounted for about 1 per cent of the population, so that although there were issues with Jewish settlement in the early 20th century that superficially resemble the concerns of today's natives, the differences are noticeable. Under Labour, partly because of immigration changes that were made to win favour with community leaders, the total Muslim population of Britain doubled to 4.6 per cent. It will pass 8 per cent before the end of the next decade.