The UK coronavirus death toll would have been halved if Boris Johnson had locked down just one week earlier, says his former scientific adviser

• One of Boris Johnson's former scientific advisers says the UK's death toll would have been reduced by at least half if Boris Johnson had imposed restrictions earlier.
• Professor Neil Ferguson, an epidemiologist at Imperial College London, said that around 20,000 lives could have been saved if lockdown had been introduced one week earlier.
• His warning echoes that of another SAGE committee member, Professor John Edmunds, who on Sunday expressed remorse that the UK did not enforce the lockdown sooner.
• Rory Stewart, a former Cabinet minister, was one of the most vocal advocates for an earlier lockdown in March. He said that the government should have challenged scientific advice more rigorously.

The UK's coronavirus death toll would have been reduced by at least half if Boris Johnson had imposed lockdown restrictions on the country a week earlier, according to a damning account by one of the scientists who informed the government's response at the time.

Professor Neil Ferguson, an epidemiologist at Imperial College London, said that around 20,000 lives could have been saved if lockdown had been introduced one week earlier.

"The epidemic was doubling every three to four days before interventions were introduced. Had we introduced lockdown a week earlier we'd have reduced the final death toll by at least half," he told MPs on the House of Commons science committee on Wednesday.

"The measures, given what we knew about the virus then, were warranted. Certainly had we introduced them earlier we'd have seen many fewer deaths."

The official government death toll stands at 41,128, according to figures published on Wednesday, meaning Ferguson was claiming that over 20,000 lives could have been saved by imposing a lockdown earlier.

Figures from the Office for National Statistics, an independent body, indicates the death toll could be higher still, with over 63,000 excess deaths having been recorded during the pandemic.

Ferguson sat on the SAGE committee, a group of scientists advising the government on Covid-19, and was a leading architect of the lockdown plan until he resigned after breaking lockdown rules to meet his lover.

His warning echoes that of another SAGE committee member, Professor John Edmunds, who on Sunday expressed remorse that the UK did not enforce the lockdown sooner.

"We should have gone into lockdown earlier," he told the BBC's Andrew Marr programme on Sunday.

"I think it would have been hard to do it. I think the data that we were dealing with from the early part of March and the kind of situational awareness was really quite poor. And I think it would have been very hard to pull the trigger at that point. But I wish we had."

"I wish we had gone into lockdown earlier, I think that it's cost a lot of lives, unfortunately."

Boris Johnson insisted on Wednesday that it was "premature" to judge whether the government should have acted differently, adding that politicians "made the decisions at the time on the guidance of SAGE, including Professor Ferguson."

Rory Stewart, a former Cabinet minister, was one of the most vocal advocates for an earlier lockdown in March. He said that the government should have challenged scientific advice more rigorously.

"It's right that they did follow the scientific advice, but it's also true I believe that from the end of February they should have been challenging it harder on the basis of what they could see was happening elsewhere," he told BBC's Today programme on Thursday.