Britain’s post-Brexit trade deal with the EU cleared its last political hurdle on Wednesday, after the European Parliament approved it by an overwhelming majority.

MEPs backed the future-relationship deal with 660 votes in favour, five against and 32 abstentions, even as they branded Brexit a “historic mistake”. The vote removes any legal uncertainty around the deal, which has been in provisional effect since the start of this year and which ensures tariff-free trade without quotas for British and EU-made goods.

The 1,449 page trade and co-operation agreement was hammered out by Boris Johnson’s government and the EU last year, culminating in frantic negotiations in December to get a deal over the line before Britain left the EU single market and customs union on January 1.

The announcement of the EU parliament’s ratification vote was welcomed by Johnson as “the final step in a long journey, providing stability to our new relationship with the EU as vital trading partners, close allies and sovereign equals”.

“Now is the time to look forward to the future and to building a more global Britain,” he said.

The EU side also signalled that it hoped that vote could mark a turning point towards a positive relationship after the first few months of 2021 were marked by EU-UK spats over Northern Ireland, vaccines and diplomatic privileges.

European Council president Charles Michel said that the move, which now sets in motion the final legal acts of ratification, “opens a new era”. Ursula von der Leyen, the president of the European Commission, said that the trade deal was “the foundation of a strong and close partnership with the UK”, while cautioning that “faithful implementation is essential”.

The European Parliament vote was the culmination of months of reflection by the assembly on when to adopt the text. MEPs in December ruled out a vote before the end of the year, despite the UK parliament approving the deal in one day in late December.

Plans for a vote earlier this year were then put on ice after Britain took unilateral decisions on Northern Ireland trading arrangements that Brussels said violated the EU-UK divorce treaty, agreed in 2019.

Leading EU policymakers including Brexit commissioner Maros Sefcovic have in recent weeks quietly urged the parliament to proceed with a vote, partly on the grounds that it would open up new possibilities for the EU to sanction any future breaches of good faith by London, including by hitting UK goods with punitive tariffs.

Sefcovic has also pointed to a recent upturn in relations, with both sides now working jointly on solutions on how to implement post-Brexit arrangements for Northern Ireland.

Christophe Hansen, one of the European Parliament’s two lead MEPs on the trade deal, said that it was an exercise in “damage control” from Brexit.

“Time now to turn the self-destructive Brexit page and look forward to constructive co-operation,” he said on Twitter.

Lord David Frost, the UK minister overseeing Brexit affairs, thanked the EU’s former Brexit negotiator Michel Barnier for helping negotiate the deal and added: “Hope we can now begin a new chapter together as Europeans, characterised by friendly co-operation between sovereign equals.”