A new Covid Alert System with five levels would influence how quickly the lockdown – which was first announced on 23 March – could be changed.
The first step will allow people to take unlimited amounts of outdoor exercise, sit or sunbathe in parks and play sports with household members from Wednesday.
The changes in guidelines will also allow two people from different households to meet in a park if they stay two metres apart.
He hoped by the second step – “at the earliest by 1 June” – there could be a phased reopening of shops and some primary aged pupils could return to school.
The third step could see some hospitality businesses and other public places reopen – “if the numbers support it” – but not earlier than 1 July.
The prime minister stressed this was all “conditional” on a series of “big ifs” and he would not hesitate to “put on the brakes” if there are further outbreaks of the virus.
Mr Johnson is set to give a statement to Parliament on Monday, with more information expected on a Covid-19 alert system, use of face masks, and the return of professional football.
But Sir Keir said Mr Johnson’s speech raised “as many questions as it answers”.
‘Trying to pull off the impossible’
The prime minister is effectively trying to pull off the impossible. He wants to try to restart normal life, while keeping the virus at bay with limited means to do so.
With no vaccine, the government is reliant on containing any local outbreaks.
But the problem is that even with the extra testing that has been put in place over the past month, there are big holes in the UK’s ability to suppress the virus. It takes too long to get test results back – several days in some cases – and those most in need of regular testing, such as care home staff for example, are still reporting they cannot always access tests.
Our ability to trace the close contacts of infected people remains unknown – the piloting of the system, which involves the use of an app and army of contact tracers, has just started on the Isle of Wight. It means we are effectively fighting this “invisible killer” with one hand behind our back.
We are not alone in struggling, similar problems are being encountered by other countries. But we are still some way behind the best prepared and equipped, such as Germany and South Korea.
Labour’s shadow business secretary Ed Miliband and shadow employment rights minister Andy McDonald said they were “deeply concerned” about the recommendation that those people unable to work from home should go back to work.
In a letter to Business Secretary Alok Sharma, they said urging staff to return to work with 12 hours’ notice and no guidance on how they could stay safe was “irresponsible and wrong”.
They called on the government to publish its guidance and ensure it addressed measures such as safe social distancing in the workplace and mandatory Covid-19 risk assessments.
‘Stay at home’
Mr Johnson said he had consulted “across the political spectrum, across all four nations of the UK” and that his plan was a “a general consensus on what we could do”.
The Northern Ireland Executive said it would “consider its plan for a phased, strategic approach to recovery” at a meeting on Monday, with politicians there emphasising the “stay at home” message ahead of Mr Johnson’s address on Monday.
Some union leaders and business groups have criticised the plans, and called for further clarity.
The National Education Union (NEU) said the idea that some schools could reopen from 1 June was “nothing short of reckless” as the infection rate is still “far too great”.
Meanwhile, TUC general secretary Frances O’Grady said the PM’s statement would cause workers “a lot of confusion and anxiety”, and urged No 10 to provide “clear direction” for staff and employers in the form of “tough” new safety rules.