England's chief medical officer (CMO) said a "bit of realism" would be needed when telling people not to see their partners unless they lived together in the spring of 2020.

However, the government went on to issue pandemic guidance that became known as a "sex ban" for couples living in separate households - who were told to move in together or stop seeing each other while restrictions were in place.

The revelation is the latest from more than 100,000 WhatsApp messages leaked to The Telegraph by journalist Isabel Oakeshott after she helped former health secretary Matt Hancock write his book, Pandemic Diaries.

According to the newspaper, Sir Chris was asked to give "the official CMO love advice" on non-cohabiting couples during a WhatsApp discussion on 24 March - the day after then prime minister Boris Johnson ordered the nation into its first lockdown.

James Slack, then Mr Johnson's spokesman, asked: "Sorry for this, but the biggest Q of the day for our finest political journalists is: 'Can I see my boyfriend or girlfriend if we don't live in the same household?'"

Sir Patrick Vallance, the chief scientific adviser, replied saying that if contact between households was to be broken, the "strict answer is that they shouldn't meet or should bunker down in the same house".

"But Chris can give the official CMO love advice," the adviser reportedly added.

Sir Chris suggested the guidance could be more relaxed for those who did not live with a vulnerable or older person.

"I think a bit of realism will be needed," he replied in the group conversation.

"If it's a regular partner I don't think people are likely to listen to advice not to see them for three weeks or maybe more.

"We could say; if they can avoid seeing one another they should, and if either of them has an older or vulnerable person in the house they must."

Later that day, Sir Chris's deputy, Dr Jenny Harries, told a press conference that social distancing guidance should apply to non-cohabiting partners.

Speaking alongside Mr Hancock, Dr Harries said: "If you are two individuals, two halves of the couple, living in separate households then ideally they should stay in those households."

She said couples could "test" their relationship and move in together while the clampdown on movement was in place.

Mr Hancock said: "There you go. Make your choice and stick with it."

The most high-profile breach of the guidance on couples living separately was by Professor Neil Ferguson, who resigned from the government's scientific advisory group for emergencies (SAGE) after it emerged that a woman reported to be his lover had visited his home in lockdown.

The so-called "sex ban" stayed in place for almost three months, when rules were relaxed to allow some couples to see each other without following social distancing restrictions.

In June 2020, new "support bubbles" allowed people living alone to combine with another household and stay overnight.

But many restrictions remained in place for another year and proved to be the downfall of Mr Hancock, who was forced to resign as health secretary after being caught breaking social distancing rules to pursue an affair with an aide.

The Department of Health and Social Care (DHSC) said it did not comment on leaks.

A government spokesman said: "We have always said there are lessons to be learnt from the pandemic.

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"We are committed to learning from the COVID inquiry's findings, which will play a key role in informing the government's planning and preparations for the future."

Mr Hancock repeated his response that there was "absolutely no public interest case for this huge breach" and said the national inquiry was the "right, and only" place for government pandemic decision-making to be "considered properly".

Hancock's secret plan to 'bring COVID patients from France to UK during second wave'

There has been a steady stream of leaks since the first story broke last week.

The messages have reignited rows about the government's handling of the pandemic, even as Mr Hancock and others have described them as only a "partial" account.

New messages also published on Monday evening reveal Mr Hancock planned to bring COVID patients from France to the UK for treatment while the country was in its second wave of the pandemic.

The former health secretary wanted to offer "spare" intensive care beds in England to French President Emmanuel Macron as Europe grappled with a new surge of infection, according to The Telegraph.

Lockdown had been reintroduced in England at that time in a bid to prevent a "medical and moral disaster".

But on 13 November 2020, Mr Hancock shared a letter with his top advisers that he proposed to send to French health minister Olivier Veran claiming to have "spare capacity in London and the south".

The plan is not thought to have been implemented, but Mr Hancock reportedly said: "We may need to make a similar offer to Italy".