Scenarios estimating 4,000 deaths a day from coronavirus presented when the Government announced a new English lockdown have been criticised by some experts.

But another scientist said that even if those models were wrong, the country is still looking at 500 deaths a day in two to three weeks as a “best case” scenario, and warned that if nothing is done this could rise above 1,000 daily deaths before Christmas.

Professor Carl Heneghan, director of the Centre for Evidence Based Medicine at Oxford University, said that the graphs used at Saturday’s Downing Street press conference with estimates of Covid deaths were based on models from three weeks ago.

In a blog post written with Dr Daniel Howdon, senior research fellow in health economics at the University of Leeds, Prof Heneghan said one of the models had since revised down its estimated number of deaths.

The pair said on Monday that the University of Cambridge and Public Health England (PHE) model had estimated 1,000 deaths by November 1 but Government data showed an average of “just over 200”.

The university’s MRC biostatistics unit has since revised its projected deaths down from 588 on October 30 to 497 on November 15, the pair added.

The PA news agency understands that further models were submitted to Government scientific advisory groups as recently as last week.

Prof Heneghan and Dr Howdon said: “The slides leaked to the BBC on estimated Covid-19 deaths and presented at the Government press conference on the October 31 were based on different models from at least three weeks ago.

“Two SAGE [Scientific Advisory Group for Emergencies] model estimates have already proven to be invalid.

“We consider these analyses need checking with the raw data to verify the estimates against the actual death data and further verify whether the lower estimates reflect the actual data.”

Their comments came after Prime Minister Boris Johnson announced a new national lockdown in England on Saturday.

Professor James Naismith, director of the Rosalind Franklin Institute, said that because of the time lag between infections and deaths, waiting for a model to prove accurate risked further deaths if no action was taken.

He said: “What even the most optimistic models agree on is that we will see around 500 deaths per day in two to three weeks (best case). We know these deaths will happen because of the number of people infected last week.

“What matters now is how many people are going to be infected each day this week and next week. This will determine how many people die in four weeks time.”

He said predicting the future “always has uncertainty” but that we cannot afford to simply wait and see if existing measures start working.

Prof Naismith added: “If the virus continues at the rate we saw last week, then taking the two or three weeks to prove beyond any doubt that the current measures have failed, then we will be unable to avoid over 1,000 deaths a day (in a best case scenario) before Christmas. This is to put a hope over evidence and to risk at least 500 unnecessary deaths per day.”

Professor Neil Ferguson, of Imperial College London, said that the 4,000 deaths a day scenarios were “preliminary work” to create a new “reasonable worst case planning scenario”.

He added: “SPI-M [Scientific Pandemic Influenza Group on Modelling] undertakes a wide range of modelling for government.

“The ‘up to 4,000 deaths a day’ scenarios represent preliminary work to generate a new reasonable worst case planning scenario to assist NHS and other Government planning.”

He added: “Even allowing for the effects of the current tier system, the most recent SPI-M projections suggest that without further action, the second wave is set to exceed the first wave in hospital demand and deaths.”

Dr Howdon said that the variation in the different models emphasised the high degree of uncertainty but said many of them had been “a long way off” in their predictions.

He added: “What we have done is look at the data and try to compare it to reality.

“Ultimately, if you compare them [the models] to the observed reality, they have generally been a long way off.”

According to the most recent Government data published on Sunday, the UK seven-day average number of reported deaths within 28 days of a positive coronavirus test was 260 a day between October 26 to November 1.

The latest data from the Office for National Statistics (ONS) shows that the number of deaths registered in England and Wales between October 10-16 was 6.8% above the five-year average.

It was the sixth week in a row that deaths were above the five year average, according to the ONS figures.