From referendum to trade deal – the timeline of how Brexit unfolded Parliament overwhelmingly backs UK-EU agreement four years after Britain voted to leave 30 December 2020 • 8:53pm UK chief trade negotiator, David Frost looks on as Prime Minister, Boris Johnson signs the Brexit trade deal with the EU Credit: Leon Neal/Getty Images Europe After four years, three Prime Ministers and more than 40 votes in Parliament, the United Kingdom is leaving the European Union with a deal. Boris Johnson’s pledge to “Get Brexit Done” has been honoured at the eleventh hour, and his trade deal with the EU carried the support of the Labour Party through the House of Commons.