Will the UK reverse course on Brexit?
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What are the chances that the U.K. will reverse course on Brexit? Better, I suspect, than the conventional wisdom has it. Here's why:

• The Brexit referendum is not legally binding. It's purely advisory.

• Leaving the EU is against the U.K.'s national interest and threatens a post-war regime that has brought 70 years of peace and prosperity to the nation and continental Europe. This is a compelling basis for a "Bregret" (short for “British regret”) campaign to demand a second referendum.

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• Brexit represents an existential threat to the U.K. as Scotland moves to split from the country and remain in the EU, and Northern Ireland seeks to retain the benefits of EU membership and an open border with the Republic of Ireland.

• Any Brexit agreement with the EU must be approved by Parliament, and considering the weight of the matter, members of Parliament are likely to demand a vote of conscience. Also, consideration in Parliament will give Bregret supporters an opportunity to demand that voters be given final word on whether to approve the terms of the agreement. This second referendum would take place when the costs and risks of leaving the EU will be more clearly understood than they were last week.

• Scotland has a reasonably strong case that devolution gives the nation authority to block Brexit, providing a Bregret campaign another justification for demanding a second referendum.

• The shattering effect of the "Leave" victory on the Conservative and Labour parties creates a vacuum that political and business leaders who supported Remain will fill to demand a second referendum.

• The extraordinary range of changes in law, policy, business, governance and politics that are required for Brexit are only now being widely recognized. They are daunting.

• One of the principal leaders of the Leave campaign promised before the election that a 52 percent to 48 percent vote to "Remain" would not mark the end of their efforts. The final outcome happened to be 52 percent to 48 percent to Leave. As the Bregret campaign builds momentum, we'll be hearing "What's good for the goose is good for the gander."

• While Prime Minister David Cameron said before the vote that there would be no second referendum, he did so expecting a victory by Remain and to head off Leave's threat to seek additional referenda until they prevailed. Moreover, Cameron's statement means nothing since he's now a lame duck and a new government will be in place by October.

• Cameron promised a Brexit referendum to save his Conservative government in last year's parliamentary election, creating an enormous risk for his country. Bregret will argue the question was too complex to put before the people; in a representative democracy, that's Parliament's job. As one British pundit quipped about plebiscites, "Ask a stupid question, get a stupid answer."

• The apparent late shift of polls and elite opinion thought to signal a victory for Remain appears to have led some undecided voters to think it was safe to cast a protest vote for Leave. Also, Remain supporters, especially young voters, may have become overconfident and felt less compelled to go to the polls. These hypotheses are likely to be tested by polling in coming weeks, and if they prove up, a Bregret campaign will gain momentum.

• The Leave campaign dismissed warnings about the costs of Brexit and exaggerated the benefits of leaving the EU and their ability to protect communities that might suffer from Brexit. Communities that voted most heavily to Leave are also the most vulnerable to Brexit. As they wake up to how dependent they are on EU subsidies and as leaders of Leave back away from their pre-election assurances to protect them, these voters are now discovering that Leave sold them a bill of goods.

• The process by which the U.K. would implement Brexit will take more than two years, during which the harsh reality of what voters have wrought will sink in. Leave advocates admitted before the election that the U.K. economy would take a hit over the short- to mid-term, but claimed the country would benefit over the long term. As a famous British economist once said, "In the long term we're all dead." This adage applies in spades to Britain's most vulnerable local economies.

• Legal requirements that remain in effect during Brexit negotiations deny the government authority to substantially address the immigration issue that drove Leave's success. Therefore, little will change for the next several years. Leave voters will also discover that to retain the benefits of an open market with the EU, which is crucial to limiting the damage of Brexit, the U.K. may have to meet the same immigration obligations it faces today.

• In the first three days following the vote, more than 3.7 million people signed a parliamentary petition calling for a second referendum. Parliament must debate any petition that gathers 100,000 signatures. (Media sympathetic to Brexit have trumpeted the fact that 77,000 signatures were removed from the petition as fraudulent but neglected to mention that at the rate new signatures were being added, the disqualified signatures were replaced in about an hour-and-a-half.)

• What the former Prime Minister Winston Churchill said about Americans might also be said about the British: "You can always count on Americans to do the right thing — after they've tried everything else."

Diehl is a former chief of staff of the U.S. Treasury Department, director of the U.S. Mint and staff director of the Senate Finance Committee.