Millions of people across London, the south-east of England and Wales have entered a third lockdown as tier 4 restrictions came into force in the two nations amid surging Covid-19 cases.
While Christmas has effectively been cancelled for almost 18 million people in London, south-eastern and eastern England, with households banned from mixing indoors and outdoors with others, the rest of the country faces a much scaled-back festive period.
On Saturday, Boris Johnson and the leaders of Wales and Scotland announced that the previous "three households, five days" rule was being ripped up and households only able to form "bubble" for Christmas Day only.
While the law will not be changed in Northern Ireland and the five-day rule remains in place, people have been asked to form a "bubble" for Christmas Day only.
Explained: What are the new Covid-19 restrictions and which areas are in Tier 4?
The tougher measures were announced amid rising coronavirus cases.
On Saturday, a further 534 people died with 28 days of a coronavirus test while a further 27,052 people tested positive for Covid-19, bringing the UK total since the start of the pandemic to more than two million cases.
Speaking alongside Chief Medical Officer Professor Chris Whitty and Chief Scientific Advisor Sir Patrick Vallance at a Downing Street coronavirus update, Boris Johnson said the tightening of the restrictions is linked to the spread of a mutant variant of Covid-19 which scientists believe is spreading more quickly than the previous form.
Speaking during the briefing, the prime minister said people should “lift a glass to those who aren’t there”, knowing that celebrating Christmas apart this year meant there would be “a better chance that they’ll be there next year”.
Under the new Tier 4 rules in the south-east of England and alert level four in Wales, non-essential shops – as well as gyms, cinemas, casinos and hairdressers – have to stay shut and people are limited to meeting one other person from another household in an outdoor public space.
Those in Tier 4 were told they should not travel out of the region, while those outside were advised against visiting.
Scotland has said its travel ban with the rest of the UK will now remain in place right throughout the festive period.
At a Number 10 news conference on Saturday, Mr Johnson said he was taking the actions with a “heavy heart”, but the scientific evidence – suggesting the new strain was up to 70% more transmissible than the original variant – had left him with no choice.
“Without action the evidence suggests that infections would soar, hospitals would become overwhelmed and many thousands more would lose their lives,” he said.
“Yes Christmas this year will be different, very different.
"We’re sacrificing the chance to see our loved ones this Christmas so that we have a better chance of protecting their lives, so that we can see them at future Christmases.”
The announcements prompted a rush to the London train stations and by 7pm on Saturday, there were no tickets available online from several London stations including Paddington, Kings Cross and Euston.
Footage posted on social media showed large crowds at St Pancras station waiting to board trains to Leeds.
The announcements came as a hammer blow to many businesses – particularly retailers hoping to pick up some pre-Christmas sales at the end of a torrid year in which they had faced repeated orders to close.
There was also fury among some Conservative MPs after weeks of growing backbench unrest over the return of more and more stringent controls.
Mark Harper, the leader of the Covid Recovery Group of Tory MPs, demanded the recall of Parliament so MPs could debate and vote on the changes for England.
“Given the three-tier system and the initial Christmas household rules were expressly authorised by the House of Commons, these changes must also be put to a vote in the Commons at the earliest opportunity, even if that means a recall of the House, ” he said.
British Medical Association council chair Dr Chaand Nagpaul however welcomed the announcement which, he said, would save lives and help health services cope with “incredible demand”.
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The dramatic move came after scientists on the Government’s New and Emerging Respiratory Virus Threats Advisory Group (Nervtag) concluded the mutant strain identified by the Public Health England laboratories at Porton Down was spreading more quickly.
The prime minister was advised of the group’s conclusions at a meeting with ministers on the Covid O Committee on Friday evening, and the new regulations were signed off by the Cabinet in a conference call on Saturday.
The UK also informed the World Health Organization of its findings.
ITV News Political Editor Robert Peston reacts to the latest Covid restrictions on Saturday's News At Ten
Sir Patrick Vallance, the government’s chief scientific adviser, said the new variant, known as VUI 202012/01, was thought to have originated in either London or Kent in September.
By November, it was accounting for 28% of new infections in the region and by early December that had risen to 60%.
“This new variant not only moves fast but it is becoming the dominant variant,” he said.
He said however there was no evidence it causes a more severe illness than the original virus, while the “working assumption ” of scientists was that the vaccines that had been developed should be able to deal with it.