Leading Brexit backers made it sound easy for Britain to walk away from the European Union, yet keep such valuable benefits of club membership as free trade, unrestricted investment and open access for its banks. There was also an assumption that a disgruntled Scotland and Northern Ireland, which supported staying in the EU, would grudgingly fall into line after the vote.
Britons are about to discover just how complicated and perilous their chosen path will be and what the political and economic repercussions could be not only for a disunited kingdom but other restive European countries facing their own populist backlash over such vexing issues as the Syrian refugee crisis and chronic economic malaise.
There are enough known unknowns and unknown unknowns on this rock-strewn trail to evoke memories of then-U.S. defence secretary Donald Rumsfeld's famous comment in 2002 about whether Iraq supplied weapons of mass destruction to terrorists.
The net result of so many unanswered questions is raising anxiety around the world about the effects on everything from the stability of the European alliance and the health of volatile financial markets to the geopolitical ambitions of Russian President Vladimir Putin, who could try to exploit the fractures in Europe.
Britain itself may also end up severely weakened and not just economically. Scottish First Minister Nicola Sturgeon is eager to keep Scotland under the EU umbrella and says the Scottish Parliament could withhold its support. Under its devolution deal, the Scots can reject changes to the pact that would be necessitated by Brexit, such as adherence to EU rules. But they can't block the actual departure.
Brussels, for its part, has no provision for any part of Britain to inherit its seat. On paper, all of Britain either stays or goes. But legal experts say Ms. Sturgeon's government could begin such negotiations informally as part of a transition to Scottish independence, a mandate she would almost certainly seek.
Meanwhile, in Northern Ireland, where 56 per cent of voters opted to remain in the EU, republican politicians are reviving another long-held ambition – union with EU member Ireland. But Northern Ireland's First Minister, Arlene Foster, campaigned for the Leave side, making another outcome more likely: thousands of people living along the Irish border seeking Irish passports.
Sinn Fein politician John O'Dowd told the BBC that "the islands are divided like they have never been divided before."
Britain can start the process to quit the EU simply by invoking Article 50 of the Treaty on European Union, which sets in motion a two-year timetable for a negotiated departure. It has never been tested. If no deal is reached on key trade, investment, immigration or other issues after two years, an extension would have to be approved by all remaining members. If even one country objected, Britain would be frog-marched to the exit.
To retain any of its existing EU trade, investment, financial services, scientific funding or other benefits enshrined in dozens of agreements, Britain would then face tough negotiations that could be derailed by a single No from an EU member.
Brexiters assumed Prime Minister David Cameron would take care of all that, but he has wisely chosen to resign by October, leaving the politically unpalatable task to his successor, who would first have to get Parliament to approve what, in fact, was a non-binding referendum.
Mr. Cameron has ruled out a do-over plebiscite, now that Brexiters have a better understanding of the political and economic havoc their vote has unleashed. Could Parliament, where a majority supported remaining, overrule the vote? It's one of the unknowns.
Immigration and refugees
Rising public anger over immigration and the EU's muddled refugee policy, fuelled by the blatantly racist propaganda of the U.K. Independence Party and its EU-despising Leader, Nigel Farage, became the hot-button issue of the referendum campaign. Only by leaving the EU, Brexiters argued, could Britain regain control of its borders and slash the number of job-stealing migrants, including those coming in at will from poorer former Soviet-bloc members of the EU.
It's the same impulse driving the recent successes of populist parties across Eastern Europe, France, the Netherlands and Denmark, all of which have been buoyed by the British result. Most of the arguments have little or no basis in fact.
There is no denying that migration has increased dramatically. More than two million citizens from other EU countries now work in Britain. But this trend has been under way for two decades, the jobless rate has actually declined and consumer spending has risen. Almost half of the migrants come from better-off countries. And of those, a majority have university degrees. About one-quarter of arrivals from Eastern Europe are similarly well-educated.
Apart from Mr. Cameron's career, the plunging British pound is the most obvious early victim of the referendum result. Market shocks are bound to trigger stampedes for the exits by jittery investors and momentum traders.
The contagion can spread quickly, but it's lingering uncertainty that keeps money on the sidelines. And Britain's political and economic outlook has rarely seemed so murky.
Leading Brexiter Boris Johnson oddly suggested on Monday that the pound was now stable, even as it continued its nosedive. Chancellor of the Exchequer George Osborne didn't do any better when he finally made his first public comments since the vote. His attempts to soothe rattled investors failed to arrest the slide in the currency, which fell to a 31-year low against the U.S. dollar and more than a two-year low against the euro.
The latter is taking its own pounding against other major currencies, as worried institutional money flocks to such preferred havens in stormy seas as the greenback and the Japanese yen. The result will be weaker exports for Japan and the United States and further trade woes as countries seek to devalue their own currencies.
The loonie has been caught in the fallout, through a combination of the stronger U.S. dollar, faltering stocks and lower oil prices, stemming from concerns about economic weakness spreading across Europe and around the world.
The Brexit vote revealed a stunning power vacuum at the most senior levels of both the governing Conservatives and Opposition Labour. Neither had a post-Brexit strategy and both seem to be coming apart at the seams.
Brexit-backing MPs in the Conservative ranks have freely acknowledged there is no political plan for what to do now. And such leading Leave voices as aspiring PM Mr. Johnson appear stunned by the result they fought so hard to achieve.
In the immediate aftermath of the vote, Bank of England Governor Mark Carney was the only official to take to the airwaves, issuing a calming statement about the central bank's preparedness for such an outcome and contingency plans to pump more than £250-billion ($432.5-billion) into the financial system, if needed, to ensure it keeps running smoothly.
Leading British politicians still seem shell-shocked, including Labour Leader Jeremy Corbyn, who is facing a full-scale revolt from senior party members over his lacklustre support of the Remain side. Labour-held constituencies in a large swath of England voted heavily for Brexit. And now party heavyweights fear a wipeout in the next general election, which is bound to be coming soon.