Boris Johnson has said the delayed date of July 19th for Covid-19 unlocking is a "terminus date" - suggesting the roadmap will not face further delays.
Speaking at a Downing Street briefing, the Prime Minister strongly said he intended the four week delay to be the last one.
And he said that while June 21 had been a 'not before' date, he believed July 19 was a final date.
"I'm pretty confident that July 19 will be a terminus date and we will be able to take things forward from there."
He said: "We have reasons to be confident, looking at the scale of the vaccine roll-out, looking at, as Patrick was saying, looking at the levels of protection they give."
Earlier, the Prime Minister’s official spokesman said there has been a “rapid acceleration in cases” - and experts believe England could suffer a wave of hospitalisations as bad as the first wave last April if step four went ahead on June 21.
Nationally there are around 8,000 new cases per day, the highest since February.
Ministers have been told cases are growing at 70% week-on-week and in around a third of the country, are doubling every week.
Hospitalisations are increasing by 15% week-on-week and by 66% in the North West.
More than 3,000 new UK patients per day were being admitted at the height of the first wave - compared to under 200 a day now.
The Prime Minister suggested people may wish to continue social distancing even after restrictions are relaxed.
He said: "People may want to keep maintaining social distancing, they may want to keep being sensible.
"But as far as I can see we will be in a much better position as a country to go forward with the full opening up that we envisage."
And Mr Johnson said there was always the possibility of a new variant derailing the process.
"At a certain stage, we are going to have to learn to live with the virus and to manage it as best we can," he said.
"What we are trying to do now, by this delay, is to reduce the current surge and we think we can do that - we think a two-week delay would make a substantial difference and a four-week delay would make even more of a difference in reducing the overall number of deaths."
By July 19 there will be a ``very considerable wall of immunity around the whole of the population''.
"At that stage, on the basis of the evidence that I can see now, I'm confident that we will be able to go forward with the full Step 4, the full opening."
But he added: "That, of course, does not exclude the possibility - I'm afraid, and we have got to be honest about this - the possibility that there is some new variant that is far more dangerous, that kills people in a way that we currently cannot foresee or understand."