Prof Neil Ferguson has quit as a government adviser on coronavirus after admitting an “error of judgement”.
Prof Ferguson, whose advice to the prime minister led to the UK lockdown, said he regretted “undermining” the messages on social distancing.
The Telegraph reported that a woman he was said to be in a relationship with visited his home in lockdown.
His modelling of the virus’s transmission suggested 250,000 people could die without drastic action.
This led Prime Minister Boris Johnson to announce on 23 March that he was imposing widespread curbs on daily life aimed at stopping the spread of the virus.
Under those measures people were told to go out as little as possible, with partners who live separately later being told they should “ideally” stay in their own homes.
In a statement, Prof Ferguson said: “I accept I made an error of judgement and took the wrong course of action.
“I have therefore stepped back from my involvement in Sage (Scientific Advisory Group for Emergencies).
“I acted in the belief that I was immune, having tested positive for coronavirus and completely isolated myself for almost two weeks after developing symptoms.
“I deeply regret any undermining of the clear messages around the continued need for social distancing.”
He also called the government advice on social distancing “unequivocal”, adding that it was there “to protect all of us”.
The Telegraph reported that Antonia Staats visited his home on at least two occasions during the lockdown.
Security Minister James Brokenshire told the BBC, while he was “sad to see this development”, Prof Ferguson had “taken the right course of action” by resigning.
Mr Brokenshire also stressed the importance of “ensuring there is a clarity of message on upholding the rules and requirements on social distancing and just why that matters so much in terms of protecting our NHS and saving lives”.
“We have a range of experts that will continue to support ministers,” he added.
Despite Prof Ferguson’s comments, it is currently unclear whether people who have recovered from the virus will be immune or able to catch it again.
BBC medical correspondent Fergus Walsh said “Neil Ferguson will know the science is very much developing” on immunity – and the government was not advising people to carry on as normal if they had already had the disease.
Our correspondent added that Prof Ferguson’s resignation was “a really big deal”, calling him “the most influential scientist” in the virus outbreak apart from the UK’s chief medical adviser, Prof Chris Whitty, and chief scientific adviser Sir Patrick Vallance.
However, Sir Robert Lechler, president of the academy of medical sciences, said he did not think Prof Ferguson’s resignation would “have any material impact” on the work of Sage, which is advising the government on the pandemic.
He told the BBC that Prof Ferguson had made “an important contribution” but he was sure the group would “continue to provide valuable input”.
It comes after the number of people who have died with coronavirus in the UK reached 29,427 on Tuesday – the highest number of virus deaths in Europe.
However, figures from the Office for National Statistics – which includes deaths where the virus is suspected, not just where tests have been carried out – brings the total number to more than 32,000.
Later on Wednesday, Boris Johnson will return to Prime Minister’s Questions for the first time since recovering from Covid-19. He will likely face questions from new Labour leader Sir Keir Starmer on the government’s handling of the crisis.
‘Like it doesn’t count for you’
Prof Ferguson’s resignation comes a month after Scotland’s chief medical officer, Dr Catherine Calderwood, quit when it was revealed she had broke lockdown rules by making two trips to her second home.
Scottish National Party MP Philippa Whitford compared the two cases on BBC Newsnight, saying Dr Calderwood was “also a great loss to the Scottish government”.
“But the problem is you can’t have that you’re telling people to do something really difficult but it’s as if it doesn’t count for you,” she added.
Shadow health secretary Jonathan Ashworth said he would not comment on an individual’s private life.
But he told BBC Breakfast: “Obviously we should all be following the social distancing rules because it’s absolutely vital that we all do what we can to suppress this virus.”
Prof Neil Ferguson is one of the world’s most influential disease modellers.
He is director of the MRC Centre for Global Infectious Disease Analysis.
The centre’s mathematical predictions advise governments and the World Health Organization on outbreaks from Ebola in West Africa to the current pandemic.
It was that group’s work, in early January, that alerted the world to the threat of coronavirus.
It showed hundreds if not thousands of people were likely to have been infected in Wuhan, at a time when Chinese officials said there were only a few dozen cases.
But he shot to public attention as “Professor Lockdown”.
In mid-March, the maths showed the UK needed to change course or a quarter of a million people would die in a “catastrophic epidemic”.
Those calculations helped transform government policy and all lives.
In other developments:
- On Sunday Prime Minister Boris Johnson will set out a “road map” of how the country will come out of lockdown
- The UK economy should be rebuilt in a “green” way after the virus crisis, the government’s climate change advisers have said
- The Times newspaper reports that Chancellor Rishi Sunak is considering winding down the government’s furlough scheme from July
- Most businesses reckon they need just three weeks’ notice to restart work, according to a survey
- Former Prime Minister Theresa May has criticised world leaders for failing “to forge a coherent international response” to the pandemic.
Conservative MP Sir John Redwood suggested the circumstances behind Prof Ferguson’s resignation would not matter to the public.
“What matters to the nation is are we getting the right advice and how do we get through this dreadful crisis?” he said.
Prof Ferguson led Imperial College London’s Covid-19 response team, which published research in March warning 250,000 people could die without any action, before the government imposed the lockdown.
He specialises in infectious disease and has used mathematical modelling to provide information on disease outbreaks for the past 25 years.
He carried out modelling on the foot-and-mouth disease outbreak in 2001, and in the same year was awarded an OBE. He also provided data for the government during the bird flu outbreak in 2006 and swine flu in 2009.
A statement from the university said Prof Ferguson “continues to focus on his important research”.