Britain on Friday began a new life outside the European Union after leaving the bloc's single market trading rules to go it alone for the first time in nearly half a century.
Brexit, which has dominated politics on both sides of the Channel since 2016, became reality an hour before midnight, ending the UK's 48-year obligation to follow Brussels' rules.
Free movement of more than 500 million people between Britain and the 27 EU states ended. More rigorous customs checks returned for the first time in decades, despite the hard-fought brokering of a tariff and quota-free trade deal.
Prime Minister Boris Johnson, writing in Friday's Daily Telegraph, said that Brexit presented "opportunities unknown to modern memory".
He said Britain had been given "a safe European home" since joining the then Common Market in 1973, but that "the world has changed out of all recognition, and so has the UK".
"We need to keep pace with developments on the west coast of America and in the Pearl River delta," he said. "We need the Brexit-given chance to turbo-charge those sectors in which we excel."
Early reports at Britain's borders, particularly the key Channel seaports, suggested traffic was running smoothly despite fears of hold-ups.
Hundreds of lorries crossed into France and left the country for the UK through the Channel Tunnel while dozens more were carried on ferries, with no reports of problems.
Almost 200 lorries passed through the tunnel after Britain formally left the EU Customs union and single market at midnight in the final act of its exit from the EU, operator Getlink said.
The first ferry to set sail for France under the new arrangements, The Pride of Kent of P&O Ferries, docked in Calais mid-morning.
"The traffic was strong enough for an exceptional and historic night, everything went well," a spokesperson for Getlink told AFP.
"All the trucks completed the formalities" required by the fact Britain is no longer part of the EU Customs union.
"None of the lorries were sent back," the spokesperson said.
Few immediate problems had been envisaged, with New Year's Day a public holiday followed by a weekend, and the government having announced the phased introduction of checks.
"The traffic forecast for the next few days is very light," said John Keefe, spokesman for Eurotunnel, which transports freight, cars and coaches under the Channel.
As the first ferry left the port of Dover early on Friday, truckers rolling into Calais had to deal for the first time with the new rules for transporting goods to and from mainland Europe.
The Road Haulage Association, an industry body, estimates that about 220 million new forms will need to be filled in every year to allow trade to flow with EU countries, including permits to even drive on the roads leading to ports like Dover.
"This is a revolutionary change," Rod McKenzie, managing director of public policy at the RHA, told The Times newspaper this week.
Other practical changes include how long Britons can visit their holiday homes on the continent, to travel with pets, and an end to British involvement in an EU student programme.
Tourists and business travellers, used to seamless EU travel, could face delays, although fears Britons will have to get international permits to drive in Europe were averted by a separate accord.
British fishermen are disgruntled at a compromise in the free trade agreement to allow continued access for EU boats in British waters, which raised fears of clashes at sea.
The UK's financial services sector also faces an anxious wait to learn on what basis it can keep dealing with Europe, after being largely omitted from the trade deal along with services, which account for 80 per cent of Britain's economy.
In Northern Ireland, the border with Ireland will be closely watched to ensure movement is unrestricted -- key to a 1998 peace deal that ended 30 years of violence over British rule.
And in pro-EU Scotland, First Minister Nicola Sturgeon gave a clear sign of a looming battle ahead for a new vote on independence.
"Scotland will be back soon, Europe. Keep the light on," she tweeted.
Divisions over Brexit, political and social, are deep and are likely to last for years, despite a muted end to the saga overshadowed by the global health crisis.
Opinion polls indicate that most Britons want to move on and are far more worried about the worsening coronavirus pandemic.