NUMBER 10 has furiously denied claims that Boris Johnson’s most senior adviser suggested letting pensioners die was a price worth paying to protect the economy.

A report in yesterday’s Sunday Times said that at a private engagement at the end of February, Dominic Cummings outlined the Government’s strategy for tackling the coronavirus outbreak.

One person present said it amounted to “herd immunity, protect the economy and if that means some pensioners die, too bad”. That quote – often incorrectly attributed to Cummings – was spread far and wide on social media yesterday.

A Downing Street spokesman moved quickly to deny the report: “This is a highly defamatory fabrication which was not put to Number 10 by the Sunday Times before publication. The article also includes a series of apparent quotes from meetings which are invented.”

But it is not disputed that in the past 10 days the UK Government, and Cummings, radically changed approach on how to deal with the outbreak.

That change came on March 12 when the Strategic Advisory Group of Experts (Sage) examined modelling from experts at Imperial College London, and realised that their initial estimates were massively wrong. A week earlier, the death toll was estimated to be about 100,000. But this new modelling revealed that unmitigated – if the government did nothing at all – the actual number of fatalities would be closer to 510,000.

Even if mitigated and the government took some action it would still be around 250,000.

Before that meeting the government’s philosophy was based on herd immunity – allowing a large percentage of the population to become infected, with the theory being that once they’ve recovered or they’ve been vaccinated against coronavirus, the pool of people who can catch the disease has been reduced.

This, the theory goes, would prevent a much worse second wave of the disease next winter.

Sir Patrick Vallance, the UK Government’s chief scientific adviser, said that about 60% of the population would need to get the coronavirus in order to get a herd immunity effect. However, at the March 12 meeting, Cummings, in what one of the paper’s sources dubs a “Domoscene conversion”, Cummings changed his mind. By Friday last week, the advisor had become the most outspoken advocate of a tough crackdown.

“Dominic himself had a conversion,” a senior Tory said. “He’s gone from ‘herd immunity and let the old people die’, to ‘let’s shut down the country and the economy.’”

Over the past week, the Prime Minister has announced tougher measures, including closing all schools in England, and forcing all pubs, cafes and restaurants to shut.

However, Johnson reportedly spent the week resisting Cummings’s demands for a full-blown lockdown of London, which would have included banning inhabitants from travelling outside the city.

Whitehall officials are, however, now drawing up lists of key workers who would be issued with a travel permit if a full crackdown follows.

Officials have also been working on a “lockdown list” of products that must be manufactured by law.

Ministers hope the the measures introduced last week will reduce the likely death toll from Covid-19 to “a bad seasonal flu”, which means tens, not hundreds, of thousands of deaths.

Meanwhile, Foreign Secretary Dominic Raab has been appointed “designated survivor” if Johnson comes down with the virus.

The move has been controversial in cabinet, with supporters of Michael Gove saying it should have been him.

Raab has twice tested negative for Covid-19, after coming down with a cough. Johnson has not yet been tested for the illness.

One unnamed minister told the Sunday Times: “If Boris can’t do his job because he is incapacitated, a lot of people think that Michael should be running the show, not Raab. One of these people is Michael, of course.”