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Boris Johnson could have cut the coronavirus death toll by half if lockdown measures were brought in just one week earlier, leading scientist Neil Ferguson has said. 

The professor of mathematical biology, who works at Imperial College London, said in March the epidemic was doubling every three to four days. 

The prime minister announced lockdown on March 23 but Ferguson – who was himself forced to resign as a scientific adviser when he broke lockdown rules by allowing a woman to visit him at his London home  – said restrictions seven days earlier would have halved the number of deaths.

Speaking to the Commons science and technology committee on Wednesday, he said: “The epidemic was doubling every three to four days before lockdown interventions were introduced.

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

Ferguson added, however, that based on what was known about transmission and fatalities at the time, the measures were warranted.

Speaking on March 16, a week before imposing restrictions such as school closures and business shutdowns, the PM said the government’s actions were “based scrupulously on the best scientific advice”. 

Johnson asked people to avoid all unnecessary contact and said those with symptoms should isolate for two weeks. 

He also told the public the government was choosing the “right moment” for fresh measures, saying: “And if you ask, why are we doing this now, why now, why not earlier, or later? Why bring in this very draconian measure?

“The answer is that we are asking people to do something that is difficult and disruptive of their lives.

“And the right moment, as we’ve always said, is to do it when it is most effective, when we think it can make the biggest difference to slowing the spread of the disease, reducing the number of victims, reducing the number of fatalities.”

An Imperial College London study modelling the potential progress of the virus, which predicted 260,000 deaths without lockdown and was published on March 30 by Ferguson, is thought to have strongly influenced the PM’s view. 

The latest figures from the government show the number of people who have died across the UK after contracting coronavirus has risen by at least 109 in 24 hours. It brings the working total to 40,992.

According to the Office for National Statistics (ONS) the number of people who have died with coronavirus mentioned on their death certificate is now 51,089.

And the number of excess deaths – the number of deaths above the expected number for that time of year – stands at 63,000.