In the parable of the boy who cried wolf, we should remember that the wolf did exist. The danger was real. The boy wasn’t wrong, merely premature.

It could be the same with the realignment of British politics: frequently predicted, it has yet to happen.

Now, at last, it could be taking place before our eyes. If so, it will cause great turbulence and affect not just Britain’s relations with Europe but the long-term future of the party system at Westminster.

The immediate causes are Brexit, which has divided the Right, and the Marxist takeover of the Labour Party, which has fractured the Left. In fact, the terms right and left, which still mean so much to politicians, are becoming increasingly irrelevant to the wider public. The twentieth-century arguments between capitalism and socialism mean little to twenty-first-century voters.

As a result, Conservative and Labour, the two parties that have dominated British politics for almost one hundred years, no longer command the enthusiasm of voters as they once did.

This year’s European Parliament elections produced startling results in Britain. Together, the combined support for Conservative and Labour was just 23 percent. True, in the coming general election, the figure will be much higher: under Britain’s first-past-the-post voting system, the dice are loaded to big incumbent parties. However, the latest polls point to a combined Conservative-Labour share of around 60 percent, which would be the lowest since 1918.

Underpinning these figures is a long-term trend. Back in 1970, 42 percent of British voters identified “strongly” and 37 percent “fairly strongly” with one of the two big parties—a total of 79 percent.

Compare those with today’s figures: 9 percent of Brits identify very strongly and 28 percent fairly strongly with any political party, a total of only 37 percent.

But when the same people are asked the equivalent question about the strength of their feeling for or against Brexit, the numbers are far higher: 44 percent feel very strongly and 33 percent fairly strongly about Brexit, a total of 77 percent—much the same figures as the attitudes toward the main political parties two generations ago.

These trends combine with Brexit to provoke the current turmoil in British politics in two ways.

First, they contribute to the way the government has lost its parliamentary majority in the past few days. Tribal party loyalties are fracturing not just among the wider public but among members of Parliament (MPs) at Westminster.

Going right back to the nineteenth century, the Conservative Party has combined two impulses: an internationalist economic liberalism and a culturally traditional nationalism. When these have worked together, the Conservatives have been astonishingly successful at winning elections. When these two impulses have been in conflict—going right back to the fights over the Corn Laws in the 1840s—the party has been in trouble.

Today, that trouble is immense.

The nationalist faction has taken over completely. This is the underlying reason why Conservative Party leader and UK Prime Minister Boris Johnson has lost his majority in Parliament.

The casus belli was the vote of twenty-one MPs against his Brexit policy and their subsequent expulsion from the Conservative group in the House of Commons. Add in Amber Rudd, the cabinet minister who resigned at the weekend to join the twenty-one, and the five MPs who had already left the party, and the total number of defectors rises to 27.

All of them are, essentially, liberal internationalists. In short, Brexit has intensified the tension between the two Conservative impulses to the point where large parts of both factions cannot bear to be in the same party as each other.

The immediate consequence of this bitterness is that the prime minister has lost control of Parliament. The UK is due to leave the EU on October 31, with or without a deal on an orderly withdrawal. But MPs and peers have defied Johnson by passing a law saying that this deadline can be met only if a deal is agreed with the EU and then approved by Parliament. Otherwise, the prime minister must ask the EU for an extension of the Brexit deadline to January 2020.

Johnson’s response was to seek an early general election, in the hope of securing a majority in a new House of Commons, before October 31, so that Brexit can go ahead on time. But twice he has failed to secure the support he needs from MPs to call such an election.

One still looks likely before long, but, crucially, not until after October 31, when the chances are that Johnson will be weakened for not having fulfilled his promise of delivering Brexit on time, “do or die”.

The second immediate consequence of the weakening of tribal ties in UK politics is that the next election, whenever it takes place, could well lead to another hung parliament, in which no party enjoys an outright majority.

Unlike in many other countries, majority, single-party governments have been the norm in the UK. But two of the last three general elections have failed to produce such a majority, and the third only a narrow one.

One way or another, the Brexit saga will reach some sort of conclusion in the coming months, although the fallout and friction may last years. But the underlying shifts in Britain’s party system could take a decade or more to resolve. The long-standing contest between Conservative and Labour—both parties of historically big-tent coalitions of different notions of left and right—looks increasingly out of date.

Will it be replaced—and, if so, how, when, and with what? When the dust settles will there still be two big parties—and, if so, which two? Or will fragmentation and multi-party coalitions become the norm? It is quite feasible that the process will wreck our distinctive, centuries-old character of alternating rule by large, ideologically capacious parties.

If so, the crowning irony of the Brexit drama is that British politics will end up resembling politics in much of the rest of Europe.