Prime Minister Boris Johnson has ordered a month-long lockdown from Thursday after being told the NHS was on course to become overwhelmed within five weeks amid a national resurgence of Covid-19.
From midnight on Wednesday, people in England will be asked again to "stay at home", with members of the public only allowed to leave their homes for a series of specified reasons, including education, exercise, "essential" shopping, and medical appointments.
Those who cannot work from home will be allowed to continue going to work, but Mr Johnson announced an extension of the furlough scheme until December, with the Government returning to covering up to 80 per cent of employees' wages.
"Non-essential" shops will have to close, along with entertainment venues, gyms, hairdressers, pubs, bars and restaurants – although hospitality venues will still be able to provide takeaway and delivery services.
The British Retail Consortium warned the lockdown would "cause untold damage to the high streets this close to Christmas" and "cost countless jobs".
Organised services will once again be banned at places of worship and travel abroad, except for work reasons, will be banned, although those who return from abroad from Thursday will be allowed back into the country, subject to the new rules.
The Prime Minister moved to order the lockdown, which he had previously described as a "nuclear" option, after scientific modelling suggested that all NHS beds would be full by December 4, even taking into account the extra capacity provided by the Nightingale hospitals and cancelling some non-urgent services.
On Saturday evening, Mr Johnson warned the nation the overrunning of the health service would amount to a "medical and moral disaster" with doctors and nurses having to choose which patients to treat and "who would live and who would die".
"No sensible Prime Minister can ignore the message of those figures," he insisted.
"No one wants to be imposing these kind of measures ... But we have got to be humble in the face of nature. Now is the time to take action, as there is no other choice."
On Saturday evening, Sir Patrick Vallance, the Chief Scientific Adviser to the Government, said the current wave of infections could be "twice as bad compared to the first wave", which led to the first lockdown in March.
Professor Chris Whitty, the Chief Medical Officer, warned of an increase in infections "in virtually every part of the country".
On Saturday, at an emergency meeting of the Cabinet, ministers were told by Prof Whitty and Sir Patrick that modelling suggested deaths could reach more than 4,000 a day if nothing more was done.
The Office for National Statistics estimates that 568,000 people in England are currently infected, or 1 in 100 people, compared with 1 in 2,300 in July.
The Prime Minister brought forward a formal announcement of the move after details of the plans were leaked on Saturday.
Several senior Tories accused Mr Johnson of being "bounced" into another national lockdown by longstanding advocates of a second set of national restrictions.
They warned the measures would have a "catastrophic" effect on businesses and the economy. Unlike the first lockdown, nurseries, schools and universities will remain open, and Mr Johnson urged parents to ensure that their children's education continues.
The Prime Minister also said that the shielding programme for elderly and vulnerable people will not be resumed "in the same way", having recognised "how tough shielding was" during the first wave.
Instead, those who are classed as clinically extremely vulnerable will be asked to "minimise their contact with others".
Everyone will be asked to stay at home other than for specific reasons including education, exercise, medical needs, shopping for food and essentials, providing care for vulnerable people, or escaping injury or harm.
Under the new restrictions, workplaces can remain open where people cannot work from home, with construction sites and Covid-secure factories likely to be highlighted as examples of settings that should continue to function.
Unlike in March, individuals will be able to exercise outdoors with one other person from another household. However households cannot mix in private gardens.
Funerals will be limited to 30 people, and weddings and civil partnerships will be banned except in exceptional circumstances.
Writing in The Telegraph, Sir Iain Duncan Smith, the former Conservative Party leader, described the announcement as a "body blow to the British people ... just as the economy was picking up".
He accused the Prime Minister of "giving in to the advice of his scientific advisers" without sufficiently heeding "the health of the economy".
However, Steve Baker, one previously fierce opponent of a second lockdown, said, having studied the data, it was "clear the Prime Minister and the Cabinet face exceptionally difficult choices."
On Saturday, the Cabinet was warned that infection rates were rising fastest in areas with the lowest prevalence of the virus. Although infection rates are higher in the North, it is growing "quickly or quicker" in every other part of the country, ministers were told.
The data convinced the Cabinet of the need to temporarily ditch the regional three-tier system unveiled just 20 days ago.
However, Labour said the move showed that the Prime Minister had "dithered and delayed", leading to a "lockdown longer and deeper than needed" if he had opted for national restrictions several weeks ago.
The new measures, which will be voted on in Parliament, would remain in place until December 2, when the Government will seek to ease restrictions where the virus has been brought under control.
On Saturday, Priti Patel, the Home Secretary, briefed police chiefs on the measures ahead of the public announcement.
Ministers are discussing whether to impose a more draconian ban on public protests than under the previous set of restrictions, following controversy over rallies that were allowed to take place earlier in the year.
Tory MPs opposed to the move claimed the measures would be likely to remain in place until the spring, with Sir Charles Walker, one senior backbencher, warning: "Come spring, we won't have a first world economy anymore. We won't be able to pay pensions, employ people, raise taxes, fund armies, fund police forces. Our hospitality industry will be finished. This is utterly catastrophic."
Answering concerns about the absence of a long-term strategy to cope with coronavirus, Mr Johnson insisted scientists were "optimistic" about the country's prospects in medium to long-term, based on advances with Covid-19 treatments, the possibility of an imminent vaccine, and a planned "massive expansion" in quick turnaround tests.
He said the Army was being brought in to help with the expansion of the testing programme, as part of a strategy to "stop the spread of the virus".
Mr Johnson said the overrunning of the NHS would be a “medical and moral disaster, beyond the raw loss of life”.
"Unless we act, we could see deaths in this country running at several thousand a day – a peak of mortality, alas, bigger than the one we saw in April," he said.
“Doctors and nurses would be forced to choose between saving Covid patients and non-Covid patients.
“The sheer weight of Covid demand would mean depriving tens of thousands, if not hundreds of thousands, if not millions of non-Covid patients of the care they need.”
He added: “The risk is, for the first time in our lives, the NHS will not be there for us.”
The Prime Minister said: “Christmas is going to be different this year, perhaps very different. but it’s my sincere hope and belief that by taking tough action now we can allow families across the country to be together.”
Prof Whitty warned: "We’re beginning to see a rise in the number of hospital admissions in England in virtually every age group, basically anyone over the age of 45, in an accelerating line."
Sir Patrick highlighted projections showing more people could be admitted to hospital in the next six weeks than was seenin the first wave.
Modelling suggest this would be seen “across the country as a whole” with “some hospitals earlier than others, some a bit later”, Sir Patrick warned.
The models suggest “increasing deaths over the next six weeks”, with a figure close to the first wave peak by December 8 “if nothing is done”.
NHS data presented during the press conference show that the health service was on course to exceed the currently available number of beds on around November 23.
The number of patients would then exceed the NHS's "surge" capacity, including the Nightingale hospitals, and beds freed up by postponing some non-urgent services, on around December 4.
Mr Johnson said he had briefed the devolved administrations on his plans and stood "ready to work with them on plans for Christmas and beyond.”
Nicola Sturgeon, the Scottish First Minister, said: “We will carefully consider the impact of today’s announcement in England – however, we will continue to take decisions that reflect circumstances in Scotland."