The two metre social distancing rule is "under review" the prime minister has said, as he looked ahead to the next easing of lockdown restrictions.
The government wants to reopen the hospitality industry as soon as July 4, however many firms have said the two metre rule would need to be reduced to one metre before they are able to reopen.
Many firms say it would not be possible to enforce two metre social distancing rules inside their small venues, meaning their business would be unviable if they open.
The World Health Organisation says one metre is a safe distance, but the UK government insists it is important to "move with caution" and says it will only reduce lockdown further if the "five tests" are being met.
The prime minister said the "two metres is right" currently but "we're working with the scientists to work out a moment when the numbers [of infection] are down so far that we can really say that the two metre rule is no longer necessary".
"At the moment, probably one in a thousand, maybe one in 1,600 actually have coronavirus amongst us all - the proportion will continue to get smaller and smaller," he said.
"If that happens, the risk of any of us being next to someone, whether two metres, or one metre, or one centimetre away from somebody else who has the virus, that risk becomes much, much lower."
Sir Patrick Vallance, the government's chief scientific adviser, told a media briefing that the two-metre rule is a political decision taken on advice from Sage, and that there's not likely to be any exact science on it anytime soon.
He said with ONS figures on Friday showing the number of people with new infections is still declining, and thus less chance of catching it, it may influence political decisions to lower the distance.
Before relaxing lockdown further, the government says there must be "reliable data from Sage showing that the rate of infection is decreasing to manageable levels across the board".
Boris Johnson on the R number:
The latest update from Sage suggests the rate of infection (R number) has not decreased from last week's estimate, which was between 0.7 and 0.9.A spokesman for the Prime Minister told a remote Westminster briefing: “As with all public health guidance, the two-metre rule is under constant review to ensure it reflects the latest advice from Sage.
“That will be based on also the latest evidence we have on transmission of the virus.”