Brexit Negotiations: What We Know and What We Don't

The new year was barely underway before Britain got embroiled in another Brexit row. The unexpected departure of its Brussels ambassador Ivan Rogers, and the quickfire appointment of his replacement Tim Barrow, kept the U.K. political press busy in the early January lull.

But even though the row is over, it highlights something Prime Minister Theresa May knows only too well; the Brexit negotiations are fast approaching, and time is running out for those preparing for the battle ahead.

May is much criticized for not having a plan for Brexit—on Thursday, The Economist branded her "Theresa Maybe" on a withering cover—but thanks to some revealing comments by her and her European counterparts, we do have some clues to her thinking. Here's what we know—and what we don't—about the Brexit negotiations.

We know: When it starts

It all kicks off in March. Theresa May has set herself an end of March deadline for triggering the Article 50 EU exit mechanism.

We don't know: When it ends

There's little agreement yet on what kind of "transition period," if any, Britain will try to negotiate. May and Brexit Secretary David Davis have suggested they want to wrap up both the U.K.'s exit deal and the terms of a new trading relationship within the two-year exit period following Article 50. Most experts say the latter is unlikely to happen that quickly. And even if it did, the U.K. would probably need some time to phase out EU regulations and processes and phase in new ones.

We know: May wants to reduce immigration

May has repeatedly made it clear that gaining some measure of control over immigration is to be a British priority in the negotiations. If the other EU states and Brussels stick to their current stance, that also means the U.K. will need to leave the single market—at the moment, the Europeans argue its "four freedoms" of goods, services, capital and people are indivisible.

We don't know: What happens to migrants already in the U.K.

The British government has said it wants to confirm the rights after Brexit of EU migrants who live in the country under free movement rules. But it says it can't achieve this until it gets the same guarantee about its citizens from other EU states.

We know: Britain is out of court

May has said that after Brexit, the U.K. will no longer be subject to the judgements of the European Court of Justice. That's another aim that means the U.K. will probably have to leave the single market.

We don't know: Britain could leave the Customs Union

Britain could stay within the EU's customs union after Brexit, but it's unclear whether the government wants to do so. ITV political editor Robert Peston has suggested the creation of the new Department for International Trade might mean the U.K. will leave, because members of the customs union usually cannot negotiate their own trade deals. But the department's head, Trade Secretary Liam Fox, has denied this.

We know: There's a lot we don't know

The negotiations will mean years of uncertainty. That could be very damaging for the economy.

We don't know: Whether it matters that we don't know

Many of the worst economic predictions about what would follow the Brexit vote have been proved wrong. It may be that the years of uncertainty don't have the crippling impact some fear.