A FORMER scientific adviser to the Cabinet has claimed that the UK’s grim death toll could have been cut “by at least half” if the country had gone into lockdown a week earlier.

Professor Neil Ferguson, of London’s Imperial College – who was a key part of the Scientific Advisory Group for Emergencies (Sage), until he was forced to resign after being caught flouting lockdown rules – said this could have saved the lives of around 25000 people.

Boris Johnson said the academic’s remark was “premature”.

The astonishing claim from Ferguson came at an evidence session of the House of Commons science committee.

He told MPs that the epidemic “was doubling every three to four days before lockdown interventions were introduced”.

Ferguson added: “So, had we introduced lockdown measures a week earlier, we would have reduced the final toll by at least a half.”

He added: “Whilst I think the measures, given what we knew about this virus then in terms of its transmission and its lethality, were warranted – I wouldn’t second-guess them at this point – certainly had we introduced them earlier, we would have seen many fewer deaths.”

Ferguson said he estimated that the number of deaths directly caused by coronavirus would be more than 50,000.

In March, he had estimated that the pandemic would cause at most 20,000 deaths.

This, he said, was because scientists had “underestimated how far into the epidemic this country was” back then.

“One thing the genetic data is showing us now is most chains of transmission still existing in the UK originated from Spain, to some extent Italy,” Ferguson said.

“It is clear that before we were even in a position to measure it, before surveillance systems were even set up, there were many hundreds, if not thousands, of individuals coming into the country in late February and early March from that area. And that meant that the epidemic was further ahead than we had anticipated.”

“That explains some of the acceleration of policy then. It also explains, to some extent, why mortality figures ended up being higher than we had hoped,” he added.

He also said government advisers did not anticipate how high deaths in care homes would be, as they acted on the assumption that residents would be shielded.

Asked about Ferguson’s remarks at the daily Downing Street briefing, Johnson said: “We made the decisions at the time on the guidance of Sage, including Professor Ferguson, that we thought were right for this country.

“And I think that the questions that are posed are still unanswered. And there’s a lot of data that we still, frankly, do not have.”

He added: “I know you want me to to cast judgement now on everything that happened in the months that have gone by.

“I just think that of course that moment will come and of course we’ve got to learn lessons.

“But I just think that it is at this stage premature. There’s still too much that we don’t know.

Professor Chris Whitty, the Government’s chief medical officer, said he and Ferguson both came “from a trade where looking back and working out what you would have done, knowing what you now know is absolutely routine and it’s how you improve on what you do.”

He added: “Part of the problem we had at that stage was that we had very limited information about this virus.

“There is still a lot we don’t know but we know a lot more now.”

Labour’s Jonathan Ashworth said: “The tragic reality is Boris Johnson was too slow to take us into lockdown.”

He added: “Ministers must accept they made mistakes.”