It is the start of a wonderful relationship: UK PM Boris Johnson as he signs post-Brexit trade deal with EU

 Britain and the EU signed a post-Brexit trade deal on Wednesday, setting their seal on a drawn-out divorce just hours before the UK brings its half-century European experiment to an end.

EU chiefs Ursula von der Leyen and Charles Michel, the heads of the European Commission and European Council, smiled at a brief televised ceremony to put their names to the 1,246-page Trade and Cooperation Agreement in Brussels.

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

The hefty document, bound in blue leather, was then flown by the Royal Air Force to London for Prime Minister Boris Johnson to add his signature, as the UK parliament began a rushed debate on the deal before the looming deadline.

Johnson gave a thumbs up after inking what he called "the beginning of what will be a wonderful relationship between the UK and our friends and partners in the EU".

"It's an excellent deal for this country but also for our friends and partners," he said in 10 Downing Street.

Britain will leave the European single market and customs union at 11:00 pm (2300 GMT) on Thursday, the end of a difficult year and of a post-Brexit transition period marked by intense and tortuous trade negotiations.

The lower House of Commons voted overwhelmingly by 521-73 to back the deal, despite serious opposition misgivings, and the bill was expected to pass the House of Lords later Wednesday 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.

Michel echoed the sentiment in Brussels, vowing the two sides would work "shoulder to shoulder" on major issues, including climate change and future health pandemics.

Johnson's government only published the accompanying UK legislation on Tuesday afternoon -- less than 24 hours before the debate began in parliament and an hour after the EU signing.

The government intended to ram all stages of the 85-page European Union (Future Relationship) Bill through the Commons and Lords in one day, before Queen Elizabeth II formally signs it into law.

The last-ditch deal averted the prospect of a cliff-edge separation which would have seen quotas and tariffs slapped on all cross-Channel trade, exacerbating strains in the middle of the coronavirus pandemic, which has hit Britain harder than most.

But British fishermen have accused the government of selling them out, while services -- accounting for 80 percent of the UK economy -- were largely omitted.

The City of London faces an anxious wait to learn on what basis it can continue dealing with Europe in the future.

Theresa May, whose three-year Brexit-dominated premiership ended in 2019 after she failed to win support for a closer future relationship with the bloc, voiced her unease at the agreement.

"We have a deal in trade which benefits the EU, but not a deal in services which would have benefited the UK," she told MPs.

However, an influential faction of arch-Brexiteers in Johnson's ruling Conservatives gave their blessing to the EU agreement on Tuesday, and the main opposition Labour party also gave its reluctant backing.

Despite objections among some of his own MPs, Labour leader Keir Starmer said neutrality was not an option given the stakes for Britain.

"This is a thin deal, it's got many flaws, but a thin deal is better than no deal," Starmer told MPs.

Lawmakers from the pro-European Liberal Democrats and Scottish National Party (SNP) voted against it -- with the SNP using the issue to push for a fresh referendum on independence for Scotland.

The agreement's impact will play out in the coming months, with UK businesses braced for customs red tape they have avoided for decades in cross-Channel trade.

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

Under the compressed legislative calendar, the European Parliament will 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.