Brexit two-year clock begins ticking March 29, U.K. tells EU

Secretary David Davis said. “The government is clear in its aims: a deal that works for every nation and region of the U.K. and indeed for all of Europe — a new, positive partnership between the U.K. and our friends and allies in the European Union.”

The trigger for all this tumult is the innocuous-sounding Article 50 of the EU’s Lisbon Treaty, a never-before-used mechanism for withdrawing from the bloc. British Prime Minister Theresa May, under the Article, will notify Tusk of her nation’s intentions to leave the 28-nation bloc.

The article stipulates that the two sides will have until March 2019 to agree on a divorce settlement and — if possible — establish a new relationship between Britain, the world’s No. 5 economy, and the EU, a vast single market containing 500 million people.

Britons voted in a June referendum to leave the EU after more than 40 years. But May was not able to trigger the talks until last week, when the British Parliament approved a bill authorizing the start of Brexit negotiations.

But like any divorce, things might not go to plan.

Britain doesn’t know what its fu- ture relationship with the bloc will look like — whether its businesses will freely be able to trade with the rest of Europe, its students can study abroad or its pensioners will be allowed to retire easily in other EU states. Those things have become part of life in the U.K. since 1973.

It’s also not clear what rights the estimated 3 million EU citizens already working and living in Britain will retain.

And it’s not even certain that the United Kingdom — made up of England, Scotland, Wales and Northern Ireland — will survive the EU exit intact.