Putting the UK into lockdown just one week earlier would have had a “dramatic” impact on the number of deaths caused by the Covid-19 pandemic, a leading mathematical modeller has declared.

Writing for HuffPost UK, Kit Yates, co-director of Bath University’s centre for mathematical biology, said that speedier intervention could have saved thousands of lives, while making it easier to reopen the economy and protect the NHS at the same time.

Yates underlined a new analysis by climatologist James Annan that estimated that three quarters of the UK’s fatalities – at least 27,000 deaths – would have been avoided with a lockdown imposed seven days earlier than March 23, when Boris Johnson finally opted to do so.

“In the early stages of the UK’s epidemic, when the case numbers were growing exponentially, it would not have been difficult to predict that earlier suppression would have had dramatic and beneficial consequences for the number of cases and deaths a short time down the line,” he said.

His warning came as a member of the government’s own Scientific Advisory Group on Emergencies (Sage) said he would have “loved” it if the lockdown had come into force one or two weeks earlier.

Professor Sir Ian Boyd, a professor of biology at St Andrews University, told the BBC’s Coronavirus Newscast: “I would have loved to have seen us acting a week or two weeks earlier and it would have made quite a big difference to the steepness of the curve of infection and therefore the death rate.”

Boyd suggested the government had failed to act more quickly because it based its initial assessment on the transmissibility of the SARS virus, which is less infectious than this coronavirus. It also feared the public would not respond as well to the lockdown as they did.

Latest government figures show 36,042 people with the virus have died in the UK. One model devised by the Financial Times suggests at least 63,000 excess deaths are linked directly or indirectly to Covid-19.

A growing number of scientists are pointing to modelling that suggests the UK could have had a death toll similar to Germany’s, with just 8,000 fatalities, with faster intervention.

Another study published this week by Columbia University claimed that the United States could have saved 36,000 lives with one week’s earlier lockdown.

Yates said that the UK had around “a two-week head start” in pandemic, as the situation in Italy grew worse, but it “ has still emerged from the first peak of its epidemic in a worse state than almost any other country in the world”.

“In the week before the UK enforced the lockdown, cases were growing exponentially, doubling roughly once every three-and-a-half days. This means that, over the course of a week (two doubling periods), cases would have increased four-fold,” he writes.

“Locking-down a week earlier translates to beginning lockdown with roughly a quarter of the total cases and maintaining this factor throughout as cases drop-off exponentially. A quarter of the expected cases should translate to a quarter of the expected deaths, or fewer, given that the NHS would not have been nearly so stretched.

“Not only would locking down earlier have saved thousands of lives, but it would also have decreased the time for case numbers to reach manageable levels, putting the UK in a better position to begin to re-open its economy sooner, whilst still buying time to increase NHS capacity and scale up testing.”

Yates added the key caveat that the lockdown may not have been taken so seriously if the public had not seen the impact a more developed outbreak would have had.

“However, evidence from other countries, like Australia and New Zealand, suggest that the catastrophe does not have to be unfolding on their own doorstep in order for a population to be compliant with lockdown,” he said.

Boyd told the BBC that the UK and some other European countries were “a bit slower off the mark” and less prepared than countries that had experienced SARS in the early 2000s.

“One could point the finger at ministers and politicians for not being willing to listen to scientific advice. You could point the finger at scientists for not actually being explicit enough.

“But at the end of the day all these interact with public opinion as well. And I think some politicians would have loved to have reacted earlier but in their political opinion it probably wasn’t feasible because people wouldn’t have perhaps responded in the way they eventually did.”

Professor Boyd, who was the chief scientific adviser at the environment department from 2012-19, also called on ministers to stop saying they were “led” by the science as it was “slightly misleading”.