Couples kept apart by lockdown restrictions could be reunited and some grandparents will be able to hug their grandchildren from Saturday under plans set out by Boris Johnson.

The latest move to ease England’s coronavirus lockdown will allow adults living alone or single parents to form a “support bubble” with one other household.

They would then be allowed to mix as though they were one household, spending time together indoors, not having to follow the two-metre rule and would be allowed to stay overnight.

Ministers believe the latest easing of the lockdown will help those who have been left isolated while still restricting the spread of coronavirus.

The move could allow children in single-parent households to see one set of grandparents.

A grandparent living alone would be allowed to visit the house of their child and grandchildren.

But the move would not allow a couple to visit both parents as neither household would comprise a single adult.

Officials admitted the measure was not going to benefit everyone but was targeted at those who had been left isolated by the lockdown restrictions.

At the Downing Street briefing, the Prime Minister said: “We are making this change to support those who are particularly lonely as a result of lockdown measures.

“It’s a targeted intervention to limit the most harmful effects of the current social restrictions.

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

The need to continue on the path out of lockdown was underlined by warnings the UK is on course to suffer the biggest economic hit of any developed country from the coronavirus.

The Organisation for Economic Co-operation and Development (OECD) said Britain’s economy was likely to slump by 11.5% in 2020 – but could contract by 14% if there is a second wave of Covid-19 later this year.

The stark forecast indicated the UK’s plunge in gross domestic product (GDP) will outstrip other badly impacted European countries, in a “single-hit scenario”, with falls of 11.4% expected in France, 11.1% in Spain, 11.3% in Italy and 6.6% in Germany, while the US economy is expected to shrink by 7.3% in 2020.

Meanwhile the number of deaths involving Covid-19 in the UK has passed 52,000, according to analysis of the latest available data.

The rule requiring people to stay two metres apart poses the main barrier to firms wanting to reopen when they are given permission to do so and Mr Johnson said it was being kept under review as the number of coronavirus cases comes down.

Professor Robert Dingwall, a sociologist on one of the scientific groups advising the Government, said studies into its impact did not take account of the “economic devastation” caused by the restriction or the deaths attributable to the lockdown.

The British Beer and Pub Association said the rule meant only a third of England’s pubs will be able to reopen when given permission to do so – on July 4 at the earliest – with up to 25,000 left wondering when, if ever, they will be able to serve drinkers.

At Prime Minister’s questions, Mr Johnson said: “As we drive this disease down, as we get the incidence down, working together, I want to make sure that we keep that two-metre rule under constant review.”

In other developments:

– Professor Neil Ferguson, a modelling expert who has advised the Government, said the number of deaths from coronavirus could have been halved if lockdown was introduced a week earlier.

– Projections by the NHS Confederation suggested around 10 million people will be on the waiting list for NHS treatment by the end of the year – more than double the current figure.

– Private hospitals requisitioned by the NHS will carry out cardiac operations and perform chemotherapy to help reduce waiting lists.

– Zoos and safari parks are getting ready to welcome visitors after they were given the green light to open their doors from June 15 in the latest lockdown easing.

– Mr Johnson announced a £63 million local welfare assistance fund to help “the most vulnerable families” but Labour said it only amounted to just over half the £115 million it would have cost to extend the school meal voucher scheme over the summer.

– There will be expanded and targeted coronavirus testing for frontline workers in “high-contact professions”, Mr Johnson said.

The Prime Minister continued to face pressure over the decision to abandon plans to get primary school children back in class before England’s summer break.

Labour leader Sir Keir Starmer said England is the “outlier” compared to other countries in returning children to school and hit out at the Prime Minister’s attack on trade unions over the problems in reopening classrooms.

“It’s no good the Prime Minister flailing around trying to blame others,” Sir Keir said at Prime Minister’s Questions.

At the Downing Street press conference, Mr Johnson acknowledged he was “moving slower than we would have liked in some areas”.

“The rate of infection is not yet quite low enough and because we are not able to change our social distancing advice, including smaller class sizes in schools, we are not proceeding with our ambition to bring back all primary pupils.”

Mr Johnson’s appearance at the press briefing came on the eve of the 12 week deadline he set for the country to “turn the tide” in the battle with the virus.