LONDON — Nigel Farage is the British crisis in human form. His party, the unambiguously named Brexit Party, which is hardly a party and didn’t exist six months ago, won nearly a third of the British vote in the recent European Parliament elections, putting it in first place and driving the shattered Conservative Party into fifth. Long underestimated, Mr. Farage has done more than any politician in a generation to yank British politics to the hard, nationalist right. He is one of the most effective and dangerous demagogues Britain has ever seen.

With his last political vehicle, the U.K. Independence Party, or UKIP, Mr. Farage took an assortment of Tory retirees and a smattering of ex-fascists and other right-wing cranks, and welded them into a devastating political weapon: a significant national party. That weapon tore such chunks out of the Conservatives’ share of the vote that the party leadership felt compelled to call a referendum on Europe — which it then lost. Mr. Farage declared victory and went into semiretirement as a pundit.

Now, almost three years after the Brexit vote, he’s back. His timing could hardly be better. After a “lost decade” of declining living standards and flat wage growth, trust in Parliament and the news media is at rock bottom. The Conservatives are disintegrating; Prime Minister Theresa May is on her way out of office, having failed to secure a parliamentary majority for her Brexit deal. She failed because, rather than seeking cross-party consensus, she tried to placate her own hard right and prevent voters from abandoning the party — again . Unable to do so, she has simply hardened public opinion.

A poll in April found that given a choice between remaining in the European Union, and leaving with no deal, 44 percent of Britons support “no deal.” The vast majority of these voters previously supported the Conservatives. But since they are the party of business, they can’t seriously contemplate leaving without a deal. Nor can Parliament.