“… Things fall apart; the centre cannot hold;

Mere anarchy is loosed upon the world,

… The best lack all conviction, while the worst

Are full of passionate intensity.”

– W.B. Yeats, “The Second Coming” (1919)

BRISTOL — The vote of England and Wales (though not Scotland and Northern Ireland) to leave the European Union, followed by the resignation of Prime Minister David Cameron, shocked the complacent establishment in London, in Brussels and in banks and financial markets around the world. It should not have been a surprise.

Voters in Britain were given the opportunity that voters everywhere are seeking: a chance to express their disgust with political and economic institutions that have for 30 years failed to represent and serve the interests of the majority of people in developed economies.

Originating in the Reagan-Thatcher free-market revolution of the 1980s, the decline of the middle class and of unions, the end of “living wages” and loss of jobs for skilled workers, and the steady erosion of pensions and aid to the elderly, have led to mounting, deep-seated frustration and anger. The major political parties on both sides of the Atlantic failed to recognize the problem or to stand up against the forces of globalization and income inequality.

Perhaps the one fact that most swayed opinion in the last week before the British referendum was the announcement that the U.K. population had passed 65 million, with the arrival of 500,000 immigrants in the last year. England’s share of that U.K. total is about 84 percent, or 54.8 million.

England is a bit less than 1½ times the land area of Maine. In terms of people per square mile, that means 1,089 per square mile in England, compared to 174 per square mile in Scotland and 43 per square mile in Maine.

Population growth means that Britain is expected to pass Germany in 10 years – it would have become the largest member of the EU. Clearly, there is more to fear of immigration than racism. It also reflects concern for the environment, quality of life, public services and personal incomes.

It is ironic that immigration, not inequality, was the focus of the rancorous debate in Britain before the vote to leave. Ironic because of who was leading both campaigns. They’re hard to typecast either as narrow-minded “Little Englanders” or as aristocratic elites. For examples:

Leaders of the “leave” campaign:

• Boris Johnson, Conservative former mayor of London: born in New York of Turkish, English, German and French ancestry.

• Nigel Farage, leader of the UK Independence Party: Huguenot French and German ancestry.

• Gisela Stuart, Labour member of Parliament, co-chair of Vote Leave: immigrant from Germany.

• Michael Gove, lord chancellor, Conservative member of Parliament and co-chair of Vote Leave: adopted as an infant by a Presbyterian family in Aberdeen, Scotland.

Leaders of the “remain” campaign:

• David Cameron, prime minister: of Scots and Welsh ancestry, his family’s fortune was made in Chicago in the 1880s by his Scottish grandfather.

• Stuart Rose, chair, Stronger in Europe campaign: grandparents were White Russian exiles, he grew up in Tanzania.

• Chuka Umunna, member of Parliament, Labour spokesperson: parents from Nigeria and Ireland.

• Keith Vaz, outspoken pro-Europe Labour member of Parliament: born in Aden to Portuguese-Indian parents.

We associate this kind of diversity with the United States, not a European nation-state. It reflects the fact that like the United States, Britain today is a country of immigrants. The historically inclined would suggest that has always been the case, looking back at the waves of Romans, Danes, Saxons, Normans, Huguenots, Jews and others who came to England over 2,000 years.

A further irony is that the Celtic parts of the U.K. – Scotland, Northern Ireland and the Welsh-speaking parts of Wales – are the most pro-European. The original Celtic Britons, who have been in the British Isles longest, look to Europe. Those whose families came later are more likely to think Britain does not need Europe.

Whether the British vote proves disastrous for Britain’s economy, as forecast by the “remain” campaign, remains to be seen. What can be predicted with certainty is that politics will no longer be “business as usual.” Here in the United States, the phenomenon of Donald Trump reflects similar rejection of an establishment that has become rich and powerful while leaving the middle class behind.

The U.K. polls failed to predict the vote for Brexit. The U.S. polls may also be failing to identify the extent that a protest vote may benefit Donald Trump. We now live in a world where nothing can be taken for granted.