The Government has been criticised after it emerged that key projections for Covid-19 hospital admissions and deaths presented to the public at a Downing Street press conference contained errors.

Top-end projections suggesting that daily hospital admissions in England could reach nearly 9,000 by early December, while daily deaths could hit 1,400, have both now been revised downwards.

The disclosure came after Tory MPs, led by former prime minister Theresa May, strongly criticised the way the Government used data to justify a second national lockdown in England.

However, ministers have maintained that it was the right decision, saying the NHS faced being overwhelmed if action was not taken to curb the spread of the disease.

During the Downing Street press conference on Saturday evening, chief scientific adviser Sir Patrick Vallance presented two slides showing projections for daily hospital admissions and daily deaths in England.

Both projections were by the Scientific Pandemic Influenza Group on Modelling, or SPI-M, an independent body that provides expert advice to the Government on matters relating to the UK’s response to threats from human infectious diseases.

The slide for hospital admissions in England presented by Sir Patrick showed a medium-term projection that had a top-end range of nearly 9,000 admissions a day by December 8.

But on Tuesday this slide was reissued with the top-end range revised down to just over 6,000 a day.

The Government said the amendment had taken place “after an error was found” in the ranges for the projections.

“This does not affect the insights that can be taken from these analysis,” it added.

The central projection for daily hospital admissions was unchanged on the amended slide, which showed the number reaching just over 4,000 a day by December 8.

The second slide presented by Sir Patrick on Saturday was for daily deaths in England.

This showed a projection that had a top-end range of more than 1,400 deaths a day by December 8 – well above the first-wave peak of almost 1,000.

But this slide was also reissued on Tuesday, now with the top-end range revised down to around 1,000 deaths a day by December 8.

Again, the central projection was unchanged on the amended slide, which showed daily deaths in England reaching just under 800 by December 8.

The Government said this amendment was also due “an error” in the ranges for the projections.

The disclosure came after the official statistics watchdog publicly warned Sir Patrick over the Government’s use of data during the Covid-19 pandemic.

In a letter to the chief scientist, the Office for Statistics Regulation warned that the lack of transparency surrounding some of the figures meant there was “potential to confuse the public and undermine confidence in the statistics”.

Professor Carl Heneghan, of Oxford University, went further, tweeting: “The Government’s use of data is not just confusing – the errors are positively misleading.”

Downing Street acknowledged there had been an “error” in the way the data was presented but said the underlying analysis was unchanged.

Asked if Boris Johnson still had confidence in Sir Patrick, a No 10 spokesman said: “Yes, of course.”

The spokesman added: “We want to make the data as clear and transparent as we can.

“There was no error in the underlying analysis. The consensus is that without action we will breach the first wave (peak) in terms of hospital admissions.

“We have acknowledged the mistake which we have corrected and we will continue to try and provide data in the clearest possible way.”