Brexit's happened... so what now?

What now? It's happened.

A dreary night didn't discourage those celebrating in Parliament Square. We wake this morning out of the European Union. But we follow their rules until the end of the year, without a say.

We are separate after more than 40 years, but remember much of the status quo will hold for now - the UK and the EU, the awkward couple, finally divorced - but still sharing a house and the bills.

But what the prime minister hails as a new era, a bright new dawn, starts months of hard bargaining with our neighbours across the Channel.

The UK's requests: a free trade agreement, cooperation on security, and new arrangements for fishing are just some of the vital arguments that lie ahead.

Within days, Boris Johnson - and the EU too - will set out their opening positions. And at home, the government must hurry to adapt many of our systems that are plumbed into the EU. The prime minister is adamant that process must not run beyond the end of the year.

• UK leaves the European Union

• Seven things Brexit will change and seven it won't

It's a deadline that focuses minds, but raises eyebrows. Getting meaningful agreements in place at that pace is not impossible, but hard to do.

That means while the biggest question is settled, particularly for business, uncertainty still hangs around.

But the prime minister believes the opportunity of Brexit is seeing beyond the framework of the EU. He hopes for more ability for the government to pursue its priorities at home. More freedom to act abroad - a smaller, but perhaps nimbler, partner.

And there will be fewer excuses for a British government if it fails to keep its huge promises.

Departure has been so controversial there will be plenty of rival politicians looking for early proof of failure.

In truth, the merits or mistakes of this decision will take years to show. The economy is expected to grow more slowly, but a country's value is not just measured in pounds and pence.

Brexit in a complete sense has always been hard to define. Today we will start to find out what it will really mean.