He also voiced concerns about the apparent failings in enforcement of rules and said he had asked the Home Secretary, Priti Patel, “to work with the police and others to ensure the rules which are already in place are properly enforced”.
“That means local authorities acting to close down premises and cancel events which are not following Covid-secure guidance,” he said.
The Government has ordered more police officers onto the streets to enforce the wearing of face coverings, which will become mandatory in indoor settings such as museums, galleries, cinemas and places of worship from August 8.
However, advice to encourage employers to bring staff back into work remained unchanged, with Mr Johnson saying companies have gone to “huge lengths to make workplaces safe”.
The decision to row back on the easing of lockdown came after the Prime Minister was shown data from the Office for National Statistics (ONS) on Wednesday night which revealed a rise in Covid-19 infections.
The ONS data was based on just 59 people testing positive out of 116,026 swab tests. The previous week, just 45 people tested positive out of 114,674, which meant the tipping point for a northern lockdown may have rested on only 14 extra positive tests.
The “Covid O” group of senior Cabinet ministers, along with Prof Whitty and Sir Patrick Vallance, the chief scientific adviser, agreed the changes, including tightening restrictions for parts of northern England, on Thursday night.
Muslim leaders criticised the Government for the “shockingly short notice” of the measures, announced the night before the Islamic festival of Eid al-Adha.
The Telegraph understands that Matt Hancock, the Health Secretary, raised concerns privately that over-emphasising the importance of Eid as a factor behind the decision could inflame racial tensions.
Conservative MPs have expressed worries at the decision to slow the reopening of the economy.
Mark Francois, the chairman of the European Research Group of Conservative MPs, said: “The Government’s got to stop sending contradictory signals. One day we are trying to lift the lockdown, the next we are trying to do the opposite, and the public are now rightfully confused.
“It is taxes that ultimately pay for the NHS and, if we don’t get our economy moving more quickly, we will struggle to do that in future.”