The United Kingdom has officially left the European Union after 47 years of membership, in a step cast by Prime Minister Boris Johnson as the dawn of new era.

Britain formally withdrew from the EU at 23:00 GMT on Friday, marking by both celebrations and anti-Brexit protests.

Thousands of Brexit supporters gathered outside the British parliament to celebrate the country’s departure from the EU after more than three years of wrangling. London’s Parliament Square was lined with national flags, and government buildings were lit up in the red, white and blue of the Union Jack.

Candlelit vigils were held in Scotland, which voted to stay in the EU.

In a public address ahead of Brexit, Johnson promised a new era of friendly cooperation with the European Union.

He acknowledged there may be burdens ahead, but described Brexit an opportunity for stunning success.

In the pre-recorded statement, the premier stressed that the departure is not an end but a beginning.

The most important thing to say tonight is that this is not an end but a beginning, he said.

After more than three years of wrangling, Britain remains as split over leaving the EU as it was in the 2016 referendum where Britons voted with a slight majority for their country to leave the union.

For many people this is an astonishing moment of hope, a moment they thought would never come, Johnson said.

And there are many of course who feel a sense of anxiety and loss.

And then there’s a third group, perhaps the biggest, who had started to worry that the whole political wrangle would never come to an end.

I understand all those feelings, and our job as the government -- my job -- is to bring this country together now and take us forward.

Johnson pledged to deliver a clean Brexit after winning the December 12 general election. Johnson had called for the election in order to break a deadlock in parliament, which had blocked the country’s withdrawal from the European Union, more than three and a half years after the Brexit referendum in 2016.