British Prime Minister Boris Johnson signed the post-Brexit trade deal with the European Union on Wednesday, adding his signature to that of EU chiefs after the document was flown from Brussels to London. 

"Have I read it? The answer is yes," Johnson quipped. 

Announced on December 24, the trade deal sets out the terms of Britain's new relationship with the EU following their divorce earlier this year. It will come into effect on January 1, replacing a transitional arrangement during which EU rules continued to apply to Britain. 

Britain will leave the European single market and customs union at 11 p.m. on Thursday, marking the end of a difficult year and of a post-Brexit transition period marked by intense and tortuous trade negotiations.  

The British House of Commons voted 521-73 to back the deal, despite serious opposition misgivings, and the bill was expected to pass the House of Lords later in an unusually rapid procedure. 

Introducing the legislation to ratify it, Johnson told lawmakers it heralded a new chapter for Britain and the EU as "sovereign equals, joined by friendship, commerce, history, interests and values."  

London and Brussels would work "hand in glove whenever our values and interests coincide, while fulfilling the sovereign wish of the British people to live under their own sovereign laws made by their own sovereign parliament," he added.

Previously, European Commission President Ursula von der Leyen and European Council President Charles Michel signed the deal.

"It has been a long road. It's time now to put Brexit behind us. Our future is made in Europe," said von der Leyen.

Read more: Where next for Boris Johnson after Brexit?

Consequences take shape

British fishermen have accused the government of selling them out. Services, accounting for 80 percent of the UK economy, were largely omitted, and the City of London faces an anxious wait to learn on what basis it can continue dealing with Europe in the future.

But a faction of arch-Brexiteers in Johnson's ruling Conservatives gave their blessing to the EU agreement on Tuesday, and the main opposition Labour Party signaled acquiescence, ensuring the legislation will pass.

Despite misgivings among some of his own MPs, who planned to abstain in Wednesday's vote, Labour leader Keir Starmer said neutrality was not an option given the stakes for Britain as it unwinds nearly five decades of integration with the European mainland.

"But the consequences of it are yours, and yours alone," he said, addressing Johnson's government. "We will hold you to account for it, every second you are in power."

Indeed, the full consequences of the agreement will only play out in the coming months, and UK businesses will still be grappling with the kind of customs red tape they have avoided for decades in trading across the Channel.

From January 1, there will no longer be free movement of people from Britain to the EU or vice versa.

The UK government is pulling out of a European student exchange program that has benefited tens of thousands of young people over the years.

Under the deal, musicians are not covered by exemptions allowing for free passage of short-term business visitors in the EU, sparking warnings that continental tours by UK bands will become unviable.

Many British owners of European holiday homes are finding that unless they apply for residency permits, they will face limits on how often they can visit their properties.

Under the compressed legislative calendar, the European Parliament will only debate the Brexit deal after the New Year, but they are expected to eventually nod it through. Pending that, EU member states gave their green light on Monday for the accord to take provisional effect before Thursday's deadline.

(With inputs from AFP and Reuters)