The British Prime Minister is a wrecking crew of one. Theresa May scuttled Britain’s March 29 exit from the European Union. Her preferred withdrawal option places the UK in a worse position in relation to the EU. Not content to wreak havoc in foreign relations, she is effectively destroying the Conservative party.

This is a moment to harken to Newton’s third law — “to every action there is always opposed an equal reaction.” It’s starting to look as if the third law applies in politics too, and is now in full force in Britain. Mrs. May has midwifed the Brexit party.

With Nigel Farage at its head, the Brexit party was formed when Britain failed to exit the EU as Britons — and Parliament — ordained. In a few short weeks it will contest the European Parliament elections and fight a polite but firm guerrilla campaign for Brexit in Brussels. Tories’ truculence at home augurs that Mr. Farage must take the fight to Westminster as well.

“We want the European election to be the first step of a massive change that re-steps entirely British politics and actually makes it look more like the country,” Mr. Farage told the London Sun. “MPs will realize that if they carry on trying to stop Brexit, they’ll lose their seats at the next General Election.”

The Brexit party’s leadership is hoping that current polling trends can be replicated at the national election in 2022. The most recent YouGov poll on MEP voting intentions has it leading with 28%, Labor at 22%, and the Tories far in the rear (with less than half Brexit party support) at 13%.

Conservative party brass shudder at the idea. “All party members, including elected representatives at all levels, are expected to fully support the party in all elections,” says a leaked email published by Breitbart London. “Campaigning for or endorsement of any other political party is incompatible with membership of the party.”

With Cabinet ministers rebelling from the party whip, though, why should backbenchers, let alone party chairmen and volunteers, feel obligated? Breitbart reports that even Tory MPs are exasperated by lacklustre leadership and contemplate jumping to the Brexit upstart. One senior Tory Brexiteer sent a WhatsApp message to members of the pro-Brexit European Research Group saying, “Maybe we should all just defect to the Brexit Party. Can you imagine the chaos.”

Naysayers will argue that the Brexit party will weaken Conservatives, providing the opportunity for Labor to form government. What of it? Is it preferable that the State intrude into the lives of private citizens under a Tory banner than a Labor one?

Far better for the Conservative and Brexit parties to elect members dedicated to British independence, limited government, and personal freedom — and then work in mutual aid of said principles.

“Party is a body of men united, for promoting by their joint endeavors the national interest, upon some particular principle in which they are all agreed,” Edmund Burke wrote, justifying such political association; their “duty” being “that what is right should not only be made known, but made prevalent; that what is evil should not only be detected, but defeated.”

Mr. Farage says his party presents MPs with “two choices — either they change and start to deliver Brexit, or we’ll replace them at that General Election.” Governing for its own sake is not their goal. On this basis, the Brexit party would earn Burke’s sympathy, contending for power on “honorable maxims” and “easily distinguished from the mean and interested struggle for place and emolument.”

In contrast, Burke would excoriate Mrs. May’s consultations with Labor leader Jeremy Corbyn, to “suffer” herself to be “led or controlled” by “those who contradict the very fundamental principles” for which the Tories entered office: Implementing EU withdrawal. Mr. Corbyn and his party have contempt for the 2016 referendum vote to leave and are eager to frustrate it at every opportunity.

The Conservative party has failed to deliver on popular demands for Brexit. To stumble along aimlessly — apart from enjoying the perquisites of wielding power — ill-serves its legacy. It places the “means” of political action before the “end” of conserving British institutions; it privileges the Conservative party above the sovereign nation and people it was established to serve.

Long-established parties, after all, can be trounced. America’s “Federalists” in 1800; Britain’s “Liberals” in 1918; and Canada’s “Progressive Conservatives” in 1993. Nor should it be forgotten that the “Conservative and Unionist” party came to be when Liberal Unionists formally united with Tories in 1912 to ward off Home Rule for Ireland.

It is not inconceivable that a similar future union awaits Britain’s two parties of the right.