England’s chief medical officer thought couples living in separate households were not likely to stay apart during the first weeks of the coronavirus lockdown, leaked WhatsApp messages have suggested.

Sir Chris Whitty said a “bit of realism” would be needed when telling non-cohabiting couples not to see  each other in spring 2020 as ministers looked to prevent the spread of Covid-19.

The pandemic guidance for couples living in separate households was known in the press as a “sex ban”.

The reported debate around the guidance for non-cohabiting couples is the latest set of details to emerge from the leak of Matt Hancock’s messages.

There has been a steady stream of stories from the trove of more than 100,000 WhatsApp messages provided to the Daily Telegraph by journalist Isabel Oakeshott, who co-authored Mr Hancock’s memoir the Pandemic Diaries and which covered his time as health secretary.

The reporting has reignited rows about the UK Government’s handling of the pandemic, even as Mr Hancock and others have described them as only a “partial” account.

During the latest report on the leaks, the newspaper said a group conversation — which involved Sir Chris and Sir Patrick Vallance, the UK Government’s chief scientific adviser, Mr Hancock and others — centred around the guidance for those in relationships but not living together.

James Slack, formerly Boris Johnson’s official spokesman when he was Prime Minister, asked Sir Chris and Sir Patrick whether couples could continue to see each other if they “don’t live in the same household”.

The question appeared to arise on March 24, 2020, following a briefing with Westminster’s political journalists.

Sir Patrick 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 reportedly 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.

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.

During later lockdowns, support “bubbles” were introduced, providing a way for some non-cohabiting couples to see each other without following social distancing restrictions, such as remaining two metres apart.

The bubbles allowed people living alone to combine with another household and stay overnight.

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.

“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”.

Meanwhile, Downing Street said the Prime Minister continued to have confidence in Cabinet Secretary Simon Case despite comments revealed in the leaked WhatsApp conversations.

Mr Case described Rishi Sunak, who was then chancellor, as “going bonkers” in a row over contact tracing disclosed in the messages obtained by the Telegraph.

“These are potentially areas that the independent inquiry will look at,” the Prime Minister’s official spokesman said.

“You heard the Prime Minister last week say that we won’t be getting into piecemeal bits of information, we think the inquiry is the right place to have this all set out.”

Asked about Mr Case’s style in the messages – which included him describing people going into quarantine hotels as “hilarious” and suggesting that Mr Johnson was a “nationally distrusted figure” – the spokesman again said the full context was not being shown.