A coronavirus second wave could see an extra 85,000 people die and 100,000 infected daily in Britain by Valentine's Day, according to experts.
The 'Doomsday' warning from the Scientific Advisory Board for Emergencies (SAGE), which surfaced on Wednesday, laid out a potential "worst case scenario" - though is no longer a working assumption.
It comes after a study by Imperial College London - based on random swab testing of 86,000 in England between October 16 and 25 - estimated close to one million people in Britain have the virus in any one day.
It has urged Downing Street to take drastic action to bring down the R rate - currently at almost 1.6 - down to below one and avoid more deaths.
The study found there are likely around 96,000 new infections a day, close to the levels seen in March.
The SAGE documents, meanwhile, seen by The Spectator, predicts 356,000 Covid patients may need to be hospitalised in a "large winter peak", with the wave continuing until the end of March.
These draconian measures were to remain in place until March 2021, however, scientists said schools could still remain open.
The bleak document also claimed deaths would peak at around 800 a day in late February and 25,000 could be in hospital, including 5,000 in intensive care in England by March.
While a different study green lit by the Government's Chief Scientific Adviser Sir Patrick Vallance estimated 120,000 excess fatalities during the winter.
However, the predictions were made months ago, and the bleakest working estimates for the first wave never even came true, as has often been the case in historical pandemics.
Prime Minister Boris Johnson has resisted continued pressure to fully lockdown the country, as he did in March - with Chancellor Rishi Sunak having warned about the further detrimental impact on the economy.
This is something the SAGE documents make no reference to.
However, the advisory panel has this week advised all of England must be put into Tier 3 by Christmas.
A Downing Street source told The Sun on Wednesday evening: "We all want to see families being able to celebrate Christmas and enjoy the holidays together this year.
"That’s why our regional approach is so important – we must act quickly to introduce further necessary measures that are targeted in areas where prevalence of the virus is highest.
"The most important thing people can do between now and Christmas is to remember how crucial social distancing is to stopping the spread of this virus and following all the local rules in their area."
Professor Neil Ferguson, whose modelling led to the UK going into lockdown in March, has said Tier 2 and Tier 3 areas are "unlikely to cause daily cases and deaths to fall rapidly".
It comes after SAGE's latest modelling suggests 25,000 people will be in hospital by the end of next month, exceeding the amount during the pandemic's peak in April.
In comparison, 9,199 Covid-19 patients were in England's hospital on Tuesday - while the UK saw its highest daily death toll since May 27 with 367 fatalities.
Around 200 deaths each day have been put down to the virus in Britain over the last week, a figure Sir Patrick said wouldn't be reached until the middle of November.
The Imperial College London report, published yesterday, says: "We estimate 960,000 individuals are harbouring SARS-CoV-2 virus in England on any one day.
"Whether via regional or national measures, it is now time-critical to control the virus and turn R below one if further hospital admissions and deaths from Covid-19 are to be avoided."
Lead author Professor Paul Elliott said Britain is "at a critical period in the second wave" with infection rates "worse in every region", including the South where there is "rapid growth".
"There was a period when the rate of rise was decreasing and we were hopeful that the policies that have been implemented were turning the rates down," he contiued.
"But what we see this time is an increase in the rate of rise and not only a high prevalence in the North, but rapidly increasing prevalence in the South."