People living alone in England will be able to form "support bubbles" with other households, ending weeks of isolation under lockdown.
In the latest easing of the social-distancing rules to apply from Saturday, adults living alone or single parents with children under 18 can pair up with one other household of any size.
The move has been keenly anticipated, potentially opening the way for some grandparents to visit and hug their grandchildren again.
Couples who do not live together and have been required to remain two metres apart if they met outdoors will again be able to stay overnight at each others' homes.
Announcing the plan, Boris Johnson said it was a "targeted intervention" designed to help those most isolated by the lockdown.
However, the latest batch of papers released by Britain's Scientific Advisory Group for Emergencies has revealed misgivings among the experts at the prospect.
A report of its meeting on May 13 urged "strong caution" warning it could create "significant unwanted effects" - particularly if it was introduced alongside other easing of the rules.
While the bubble plan is clearly popular with many, it is nevertheless likely to reignite concerns that the Government is moving too quickly as it seeks to re-start the economy.
The Prime Minister and his chief medical and scientific advisers have faced growing criticism that they were to slow to impose the lockdown in March, resulting in thousands of deaths.
At the same time, Mr Johnson is under intense pressure to get the economy going again amid fears that it could take years to fully recover.
The cost of the restrictions was dramatically underlined by official showing GDP shrank by a fifth in April in an unprecedented fall-off as activity ground to a halt.
The Prime Minister acknowledged the economy had been "very badly hit" but predicted it would "bounce back" as confidence returned.
However, there are fears of further job losses ahead as the Government's furlough scheme - which has seen the state pays up to 80% of employees wages - begins to unwind from August.
Australian Associated Press
