BORIS Johnson admitted he could not guarantee that England's third national lockdown will be its last.

Speaking at today's Downing Street press conference the Prime Minister said: "I can’t give that guarantee, of course not, because we are battling with nature, with a disease that is capable of mutating and changing.

Mr Johnson confirmed that he will set out "as much of a timetable as he can" next Monday (February 22) but urged people to take any speculation with "a pinch of salt".

He said that now is “no moment to relax” as ministers review coronavirus restrictions in England, while lockdown-sceptical Tory MPs press for a swift reopening.

Mr Johnson said there are “grounds for confidence” that vaccinations reduce Covid-19’s spread, but said they are awaiting the “hard facts” before setting out the timetable for easing the lockdown.

But, while saying he was “increasingly optimistic” about the possibilities to ease restrictions, the Prime Minister acknowledged he cannot guarantee it is the last lockdown.

“I’m very hopeful that we’ll be able to go ahead and open things up, but to say I can give an absolute cast iron guarantee that we won’t face further difficulties and have to think harder and deeper about some problems, no at this stage I can’t,” he said.

The Prime Minister also welcomed the news “unprecedented national achievement” of vaccinating 15 million of the most vulnerable people in the UK ahead of the target deadline.

Earlier, Mr Johnson said no decisions had been made on whether all pupils can return to school at the same time after reports suggested a staggered approach may be taken, with secondary schools going back a week later than primaries.