That means partners who live alone in separate homes can now meet up without social distancing – partially lifting the ‘sex ban’. Single parents with children under 18 are included but the change does not appear to apply to adults who live apart and in households of more than one person. The move also only applies in England, where around 11 million people live alone or as single parents.

The PM explained: ‘There are still too many people, particularly those who live by themselves who are lonely and struggling with being unable to see friends and family. From this weekend we will allow single adult households – that’s adults living alone or single parents with children under 18 – to form a support bubble with one other household. All those inner support bubbles will be able to act as though they are the same household, meaning they can stay inside each others homes and do not need to stay 2 metres apart.

The changes, which come into force from midnight on Saturday, will not apply to those who are ‘shielding’ and are designed to combat loneliness, Mr Johnson explained at the coronavirus briefing this evening. They could also allow grandparents who live alone to see grandchildren and other family members.

There had been widespread shock at the apparent sex ban, brought in on June 1, stopping people from socialising indoors – but now some adults will be able to stay overnight at another person’s home. That means it will no longer be illegal for them to have sex in their own home with someone they do not live.

It brings the Government’s stance closer to that of Holland, where single people have been advised to find ‘lockdown sex buddies’. But it could cause difficulties in shared homes, if housemates are forced to choose only one person to bring into their household ‘bubble’.

The PM, stressing loneliness and the need to see family members, clarified: ‘Support bubbles must be exclusive, meaning you can’t switch the household you are in a bubble with or connect with multiple.’

It is unclear what that means for adults living in shared houses with friends.

Mr Johnson added that the country was now meeting the ‘five tests’ the Government had previously said needed to be passed to ease the lockdown.

He continued: ‘If any member develops symptoms, all members will need to follow normal advice on household isolation. We are making this change to support those who are particularly lonely as a result of lockdown. It’s a targeted intervention to limit the most harmful effects of the current restrictions.’

‘It is emphatically not designed for people who don’t qualify to start meeting inside other peoples homes because that remains against the law.

‘Unfortunately we cannot advise anyone who is shielding to form a support bubble at this stage given their particular vulnerability to the virus.

‘I know how hard it is for those of you who are shielding, we will say more next week for the arrangements that will be in place for you.’

The PM said support bubble were ‘plainly designed’ for those who hadn’t been able to see the rest of their family for a very long time.

Chief Medical Officer Professor Chris Whitty added: ‘The idea of the bubbles is for families that have a single adult in the household, so if this applied to families with a single adult in the household that would be covered by what the Prime Minister just talked about.

‘For other people it’s largely going to have to be meeting outside and socially distanced because the risk of transmission is much lower.

‘Bubbling is about single households or lone parents, then there’s meeting outside for other people.’