Coronavirus infections are levelling off as Britain is finally starting to flatten the curve.
New infections have slowed and Government officials are now confident lockdown is working - but needs to continue to avoid collapsing the NHS.
Sources say they now believe Brits with Covid-19 are infecting on average less than one person each.
This is the crucial reproduction number (R0) threshold which, if maintained, would see the outbreak slowly die out.
New daily confirmed cases fell to 4,344 yesterday down from 5,492 the previous day.
This had been falling with 3,634 on Tuesday, 3,802 on Monday, down from the peak of 5,903 on Sunday.
However, deaths could continue to rise for a considerable period of time because they lag behind newly-diagnosed infections, and take time to be officially recorded.
Experts say this overall pattern shows we are “flattening the curve” - which was stricken PM Boris Johnson ’s mantra before he himself was hospitalised with Covid-19.
Lockdown was initiated based on Government modelling showing the reproduction number (R0) was between 2 and 2.5. This meant cases were doubling every four or five days.
A senior source leading Britain’s response to the Covid-19 crisis said: “If the R0 goes below 1, the epidemic just dies out anyway, which is hopefully what’s happening at the moment.
“I mean with social distancing that we have now you would expect it to be around 0.6. If we could stay like this it would be fine, it would just go.
“If the R0 is somewhat above 1 you can still control it with active measures.”
Daily testing is now eventually starting to be increased to around 15,000 after stalling at around the 10,000 a day mark.
Sources suggest lifting lockdown measures could potentially be considered from next month if the Government meets its 100,000 a day testing target.
That could only happen if social distancing has been maintained and hospitals are well within capacity.
Prof James Naismith, biology expert at Oxford University, said: “There is now evidence that social distancing measures are having the expected effect.
“Fewer people are getting infected which means fewer people will need intensive care which means fewer people will die.
“The lockdown has some weeks to run to bring down the number of infections and reduce pressure on the NHS.
“However prolonging the lockdown will itself have adverse health effects, delays in treatment, missed tests, increased mental illness and general disruption to care.
“Humans are social animals and social distancing is a burden that requires consent.”
Calls to NHS 111 by people with Covid-19 symptoms have been falling since March 22.
The service has been under unprecedented pressure until then with four in every ten calls abandoned due to long waits, new NHS figures showed.
Prof Keith Neal, infectious diseases expert at Nottingham University, said: “The number of cases is absolutely falling if you follow the trend.
“Hospitals are still struggling to cope with the number of cases because these people can stay ill for a number of weeks.
“We won’t be in a position to start relaxing measures at least until there is a clearance of these patients.”
Mike Tildesley, expert at Warwick University, said: “Should this trend continue we will start to have increasingly strong evidence that the social distancing measures are having an effect.
“At this point, we will need to think extremely carefully about when and how to start relaxing these measures.”
The focus is now moving move to a Government “exit strategy” which they have repeatedly refused to outline.
On mainland Europe, Denmark announced primary schools would reopen from April 15, and Austria said small shops and garden centres could open their doors again from April 14.