Returning to America after an absence of 20 years, Henry James wrote, in The American Scene (1907), of his unease at the arrival in New York of so many non-English-speaking Jews from Europe. He observed them on the street, in shops and together in their neighbourhoods and ghettos, and feared not only for the future of America but for the English language itself, especially the language of literature. “There is no swarming like that of Israel when once Israel has got a start, and the scene here bristled, at every step, with the signs and sounds, immitigable, unmistakable, of a Jewry that had burst all bounds.”

James was disconcerted by what he considered to be these new arrivals’ sense of “settled possession”, which he found “presumptuous, monstrous”, and which contrasted with his own feelings of unsettled possession. He regretted how established Americans would inevitably be forced into a kind of surrendered acceptance of cultural difference. “We must go, in other words, more than half-way to meet them; which is all the difference, for us, between possession and dispossession. This sense of dispossession haunted me.”

Following the often lurid debate about immigration and multiculturalism in this country, one sometimes feels that it is not the recent arrivals but the settled peoples of these islands who, like Henry James, feel most dispossessed, as if they are unable to understand, or feel powerless to prevent, what is happening around them.

But what exactly is happening? How rapidly and by how much is Britain really changing? We are ceaselessly told that ours is a multiracial and multicultural society. It is certainly multiracial—and all the better for it—but what does it really mean to speak of a multicultural society? Does a multicultural society mean simply a broad tolerance of difference and respect for minority cultures and traditions? Or does it mean something more assertive—the establishment, for instance, of more religious schools in Britain, of children being increasingly taught in separate religious and racial communities?

Early one Saturday afternoon at the end of February, I was travelling south on the London Underground from Tottenham Hale to King’s Cross. Sitting opposite me in the carriage of our Victoria Line train were two women of Middle Eastern appearance. They were wearing the Muslim hijab or veil and speaking very quietly in Arabic, as if embarrassed at being overheard. In the same carriage were three young black women, who, judging from their conversation, were Nigerian. They were speaking “pidgin”—a vibrant, energetic hybrid of English and, I think, Yoruba. Their hair was worn in crisp braids and threaded with intricate wooden beads. Also in the carriage were two men in their twenties, one black and the other white. The white guy, I gathered, was from a Greek-Cypriot family, but his accent was entirely local. He and his friend were both clamorous Cockneys. Beneath their jackets, they were wearing Arsenal shirts.

At the next stop, a young woman, a poor Romanian or Albanian, entered the carriage. She was wearing a headscarf, a ragged shawl and cradled a baby in her arms. She held out her hand and patiently asked each person for money. Each time, she was ignored; at the next stop, she left the train, only to be replaced by a gang of about ten youths, who, I guessed from their dark hair and scruffy swarthiness, were from the southern Balkans. They were loud, they refused to sit down, and they spoke a language I did not recognise.

Watching these boys from the Balkans as they jostled and scrapped, I did not feel threatened or uncomfortable, but I did have a strong sense of how London was being changed by the new multiculturalism and by the arrival of hundreds of thousands of people from parts of the world that had little or no affiliation to the old empire. What was taking place deep underground on this Saturday afternoon was a characteristically contemporary London scene: boisterous, polyglot, multiethnic, harmonious.

But it would not have been possible seven years ago: the forces of globalisation, more porous borders, the disintegration of Yugoslavia, the need for cheap labour, Islamic militancy, inexpensive air travel, and a second wave of mass, asylum-driven immigration mean that this is not the country it was when Labour returned to power in 1997. Something fundamental about the country has changed and is continuing to change, with theresult that it is perhaps no longer possible, indeed comprehensible, even to speak of a common British culture. Instead, we have a multiplicity of cultures, some complementary, others discrete or rivalrous.

The majority culture—anglophone, tolerant, broadly liberal, sceptical, Christian in ethos if not in practice—remains strong. But other cultures are threatening and subverting it, forcing concessions and change. Much of this change is good—such as the recognition of the rights of minorities or a respect for racial difference. But there are also areas of more problematic conflict, where the recognition of minority-group rights and identities, and the demand for exemptions from national laws, clash with a broader liberal consensus on, say, animal rights or women’s freedom.

The new cultural clash is experienced most acutely in inner-city state schools, where children from so many different ethnic backgrounds, and for whom English is often a second language, are brought uneasily together. Education is the front line where teachers and governors fight daily culture wars, in a country that has an established Church, which privileges one religion and one culture, but also has a growing and increasingly assertive Muslim minority that demands equality and legitimacy for Islam.

Britain has a strong tradition of secular government. It has, as the philosopher Roger Scruton points out (above), managed to marginalise the Christian religion “by making it into a shy adjunct of the secular state”, which has led to the withering away of religious instruction in many schools. But many Muslims, who view Islam as a revolutionary force in their lives, want their children to receive a religious education. For them, religion is not a once-weekly recreation; it is an entire politics for living.

In France, where there are perhaps six million Muslims (one-tenth of the population), the response from the state to the new multiculturalism has been to reassert the secular ideals of the Republic. This has led to the outlawing of the hijab and other obvious religious symbols in schools.

In multinational, multi-ethnic Britain, we are taught a kind of civic patriotism. From the melancholy long withdrawing roar of empire, we have learnt humility and restraint. Our sense of national identity is not based on ethnicity, on the cult of blood and soil or racial superiority. It is far more subtle and more allusive. The British way is one of resolute pragmatism, reactionary yet progressive, respectful of tradition and the accumulated wisdom of past generations, as embodied in our institutions, but also alert to the need for constant change. Our civil war was a very long time ago and our revolution was glorious.

We are not, as are the French, committed to revolutionary ideals of equality and liberty, which is why the hijab or indeed the turban would never be banned in British schools. Nor are we suspicious of the politics of the “communautaires”—communities that have separate and potentially separatist values from those of the Republic. All this, as well as the absence of a written constitution and the fragmentary nature of the British state itself, makes us endlessly adaptable—and flexible. This sense of adaptability, as well as of soft nationalism, explains in part why Britain has hitherto so successfully integrated so many new arrivals from the Caribbean, Africa, the Indian subcontinent and beyond.

The culture and the way of life of this nation, of any nation, are best understood not through grand political abstractions, but through its songs, jokes, customs, clothes, food, and games. There is something indefinable, even mystical, about national identity: we know what Britishness is, we would defend it under duress, but we would be hard-pressed to define it coherently.

It is this sense of mysterious togetherness, of a continuity of collective consciousness through time, that cultural pessimists fear is being weakened by the second wave of mass immigration, and which led the liberal intellectual David Goodhart, in an essay in Prospect, to complain that we are now too diverse. The American social policy thinker Robert Putnam has also written of how too much ethnic and cultural diversity not only weakens community ties; it weakens trust and fellow feeling, it weakens the desire to redistribute wealth because you no longer feel even the loosest affinity for those most in need. Putnam wants to see the isolated, atomised individual reintegrated into wider society, but fears that society, as once understood, no longer exists—that in our diversity we have lost our sense of common purpose and greater community.

As a child growing up in Essex in the 1970s, I knew only cultural certainties. The headmaster of my old school, a veteran of the Spanish civil war, was a socialist and atheist. “The human being,” he once told me, “is a blank sheet of paper on which any future identity can be written.” Once a week we would gather in the main hall, with its smooth, thickly varnished wooden floor, for morning assembly. We would begin by saying the Lord’s Prayer and then sing some hymns, before settling down to listen to the headmaster as he warned us about the dangers of sloth or cigarettes. He never spoke about religion.

My school was largely monocultural and monoethnic—there were two black brothers, whose parents were from the Caribbean, seven or eight Hong Kong Chinese, a Turkish Cypriot and two girls of Indian subcontinental origin. One of these girls, I recall, would sit out the morning assembly and, at the time, I could never understand why. But my school was progressive. We did not have religious education classes in which we studied the Bible; we had something called moral studies, which was a bit like reading Polly Toynbee’s columns in the Guardian: worthy but dull. These classes, I understand now, were an early concession to multiculturalism and an attempt by our socialist headmaster to fulfil certain obligations while avoiding explicit Christian instruction.

It also meant that the little Pakistani girl who missed morning assembly was quite comfortable about attending these classes.

The late 1970s and early 1980s, when I was at school, were a period of continuous dispute: the consensus politics of the postwar settlement was unravelling, there was social and civic unrest, and punk and early Thatcherism were, in their different but interrelated ways, expressions of a wider cultural disaffection, Bolshevik movements that sought renewal through radical discontinuity from the recent past.

To attend a football match at this time was to have a powerful sense that something was seriously wrong in the country: the atmosphere was invariably violent, raucous, chauvinistic and, above all, racist.

Today, by contrast, football, certainly at the highest level, is a model of cosmopolitan integration, an indicator that rapid, progressive, cultural and social change is possible. To watch Arsenal—with their French manager and their flamboyant squad of international talent—is to understand the power and attraction of multiculturalism, of diversity, hybridity and cultural slippage. Arsenal are a kind of Platonic ideal—the ultimate form of the possible.

Elsewhere, far away from Highbury, out on the streets of the more impoverished areas of London, in the ghettos of the old Lancashire mill towns, or in the small, introspective towns and villages of Middle England, one has little sense of truly cosmopolitan integration. Rather, one has a sense of people retreating into suspicious, self-contained communities.

In his book Culture and Equality: an egalitarian critique of multiculturalism (Harvard University Press), Brian Barry argues that too often “culture” can be a site of oppression—for women condemned to live unrealised lives, for animals ritually slaughtered, and for children abused in accordance with superstition or religious practice. True liberalism, he argues, is not about granting special “group-differentiated rights, privileges and entitlements”, but about enforcing citizenship and equality of opportunity for all before the law. Cultural pluralism, Barry writes, can lead to uneasy compromise and concession to private dogma in the public sphere. What are the obligations of a liberal society to those who reject liberal principles?

Barry, I suspect, would approve of the French decision to ban the hijab in schools as a reassertion of the common purpose of republican citizenship. But the banning of the hijab will solve nothing in France. The brilliant and increasingly influential young francophone philosopher Tariq Ramadan defines multiculturalism as the “Islamisation of modernity”. In France, multiculturalism is beginning to stand for—if it stands for anything at all—a divisive and negative form of revolt.

What is often forgotten or ignored in the debate about multiculturalism is that most countries in the world are multiethnic and genuinely multicultural, and must thus strive to rule by racial consensus. There are exceptions—Japan, South Korea, China, where the Han Chinese make up between 85 and 90 per cent of the population. But in the main, an important part of what it means to be human is to understand and adapt to cultural difference—ethnic, racial, tribal, linguistic, religious, territorial.

Arriving in England for the first time in the 1950s, the South African-born writer Dan Jacobson was relieved to find himself at last in the imperial metropolis, a place he could not call home, but to which he felt a deep attachment. In an essay, “Time of Arrival” (1962), he wrote of looking for a room in Hampstead and of how many notices carried discouraging messages such as “Gentiles Only” or “No Coloureds”.

“When I came here,” he says now, “England struck me as a country bound together, even made up by, a network of reciprocal ‘allusions’ (it was the only word I could think of): localities, institutions, festivals, foods, character-types, historical references and antagonisms, class indicators and suchlike. People took this network for granted, yet also half-consciously acted up to the expectations it fostered; they recognised one another through it and used it to place others in various categories—acceptable/not acceptable; belonging/not belonging. Together, it all led to the sense I had of ‘Englishness’ as something private, reserved, semiinstinctive, inherently resistant to foreign intrusions. Anyway, whether I was right or wrong about it, I thought it distinctive and interesting; and have no doubt it has taken a battering over the past half-century. But the irony—of which, as a ‘colonial’, I was always conscious—is that this same, seemingly private, reserved form of life had no hesitation in thrusting itself into other people’s territories, no matter how distant they might be, and ruling them as if by God-given right. This now gives an extra impetus to the wash-back of migration the country is experiencing.”

Jacobson, in the 1950s, could not believe that the reserved, allusive people among whom he had come to live would tolerate mass immigration. But they did and, in the main, Britain, despite its residue of serious racism, is becoming one of the most relaxed and harmonious multi-ethnic societies in the world, not least because the majority culture remains so robust and so adept at appropriating new influences and in creating new multiple identities. So just as new English cuisine has become a globalised identity, merging ingredients and styles of cooking from India, China, the Pacific Rim and from continental Europe to create what is still recognisably British food, so what it means to be British itself has become increasingly fluid and interchangeable. Yet something recognisable remains, some substratum of habit and feeling that underlies all change, and it is this mysterious something that is most valuable and gives meaning and definition to life in Britain.

Will this mysterious something endure? When Henry James left New York in 1904 to continue his travels along the east coast of America, he did so with foreboding. The “ethnic synthesis” he witnessed on the streets of Manhattan had troubled him—“here was multiplication with a vengeance”. He wrote of his “lettered anguish”, and it was as if he were already mourning the loss of the linguistic tradition he most valued. He was certain that “the accent of the ultimate future, in the States, may be destined to become the most beautiful on the globe ... but ... we shall not know it for English—in any sense for which there is an existing literary measure.”

Yet the commanding novelists of the 20th century American experience, certainly since the end of the Second World War, have been Bernard Malamud, Saul Bellow and Philip Roth, sons of Jewish migrants and the result of this ethnic synthesis, and the man who wrote the definitive account of James’s own life, and one of the greatest of all literary biographies, was none other than Leon Edel, a Jew. The problem with prediction is that, as Enoch Powell discovered and Tony Blair is discovering most calamitously, we seldom know what we think we know. What we thought was so, was not so.