It comes as thousands of scientists across the world signed the Great Barrington Declaration, calling for an end to lockdown for young and healthy people.
The Government locked down the country after Imperial modelling showed that 500,000 people could die and the NHS would be overwhelmed.
But Imperial had also predicted that no mitigation strategy could lower deaths to fewer than 200,000 without a vaccine, and suppressing the virus would merely delay an even deadlier resurgence.
The authors of the new paper, who rediscovered the figures in their reappraisal, said the Government appeared to have chosen to protect the NHS in the short term, rather than save lives throughout the whole epidemic. Although it reduced peak demand for ICU beds, it prolonged the epidemic, resulting in more long-term Covid-19 deaths.
Lead author Graeme Ackland, Professor of computer simulation at the University of Edinburgh, said: “In March the Government had to make a decision: did they want to save lives or beds?
“Lockdown does mean that the number of deaths goes down, so there is a short-term gain, but it leads to long-term pain. If you had done nothing, it would all be over by now. It would have been absolutely horrendous but it would be over. It wouldn’t even have been completely lunatic to do nothing.”
Figures showing the dangers of closing schools and blanket social distancing were reported in the original Imperial paper, but many experts did not notice them, it is claimed.
“I talked to people on SPI-M and Sage and they hadn’t seen them,” added Prof Ackland.
The Prime Minister’s spokesman said: “We have considered the full range of scientific opinion throughout the course of this pandemic and we will continue to do so.”