The UK imposed its coronavirus lockdown too late in a decision that "cost a lot of lives", a top scientific advisor to the government said today.
Prof John Edmunds, a member of the Scientific Advisory Group for Emergencies (SAGE), said the issue was his main regret in the handling of the crisis.
And he issued a stark warning to Boris Johnson not to ease the lockdown further before Covid-19 is better under control.
"It’s definitely not all over," he said. "There’s an awful long way to go and if we relax then this epidemic will come back very fast. We do need to be really cautious.”
Prof Edmunds said "poor" data back in March made it hard to "pull the trigger.. but I wish we had, I wish we had gone into lockdown earlier. I think that has cost a lot of lives, unfortunately.”
It comes amid reports the Prime Minister has drawn up further plans to ease lockdown in the coming weeks to stop millions of job losses.
Churches and places of worship will be allowed to reopen for private prayer from June 15 - the same day non-essential shops begin to reopen.
The PM is also said to be drawing up plans for outdoor and small indoor weddings, and for pubs and cafes to resume outdoor dining, in the coming weeks.
Mr Johnson will reportedly give a major speech later this month about reopening the economy, followed by an economic package from the Chancellor in July.
Yet Health Secretary Matt Hancock today admitted the coronavirus 'alert level' is still at 4 - unchanged since lockdown began on March 23.
When the alert system was unveiled on May 11, No10 said lockdown would only be relaxed when the alert level dropped to 3.
But since then the government has insisted lockdown changes are decided by a different "five test" system, and the alert level is separate.
Meanwhile modelling suggests the R number is 1.01 in the North West of England - meaning the virus is once again spreading exponentially there.
Mr Hancock insisted the model was just one among many, and on balance the government believes R is below 1 in every region.
But Greater Manchester mayor Andy Burnham warned lockdown was being eased "too soon" - and he was backed by a range of scientists and health experts today.
Niall Dickson, the chief executive of the NHS Confederation, told The Observer: "We absolutely don't want any more relaxation [of lockdown measures] until we are confident that the test and trace system is working both at national and local level."
Professor Martin Marshall, chairman of the Royal College of GPs, added: "We need a strategy for test and trace, for PPE, for the use of technology, for maintaining Covid services and opening up non-Covid services."
SAGE expert Prof Edmunds told the BBC's Andrew Marr Show: "I would still prefer to see the cases come down lower than they are at the moment.
“The ONS survey suggests we’re having around 5,000 new infections every day and that’s just in the community and just in England.
"[It is] excluding Northern Ireland, wales and Scotland, that’s excluding all the infections occurring in hospitals and care homes which are very significant numbers still.
“And so I would like to see the cases come further down, that’s my own personal opinion. But the government have to weigh these things up, of course they do.”
The UK originally tried to "delay" the spread of Covid-19 - and allowed large events like Cheltenham to go ahead - before then flipping and imposing lockdown when modelling suggested hundreds of thousands could die.
Prof Edmunds was asked by the BBC's Andrew Marr Show if he had any regrets about the UK's approach to lockdown, imposed on March 23.
He immediately replied: "Yes. We should have gone into lockdown earlier.
"I think it would have been hard to do it, I think the data we were dealing with in early parts of March and our situational awareness was really quite poor. And so I think it would have been very hard to pull the trigger at that point.
"But I wish we had, I wish we had gone into lockdown earlier. I think that has cost a lot of lives, unfortunately.”
Health Secretary Matt Hancock said he disagreed with Prof Edmunds and insisted his was only one voice in a "broad range" of opinion on SAGE.
He said: "There are others who equally make different scientific arguments.
"If you listen to the balance of opinion on SAGe, 100 people on SAGE approximately, what we do as ministers is take the scientific advice... and then we have to make the balanced judgements based on that advice. That's the way it works.
"In a body of 100 people you'll also find differing voices."
Asked if he was "sure" the timing of lockdown had not cost lives, he said: "I am sure.
"And as I keep looking back on that period, I’m sure that taking into account everything we knew at that moment, my view is we made the right decisions at the right time."