Boris Johnson said the Tier 4 restrictions weren’t strong enough to keep the coronavirus under control as the new variant spread across the country.
He said at a press conference on Downing Street that the toughest measures taken across much of England were not enough on their own to control the virus.
Mr Johnson said the government had been studying the new variant of the coronavirus in the days leading up to the lockdown announcement since it learned of its rapid spread on December 18.
The Prime Minister said it was hoped that Tier 4 measures would have an impact and allow schools to stay open.
He highlighted the latest infection numbers and added, “It was clear we got into a situation where Tier 4 cannot be relied on to get the virus under control without actually going all the way go and ask people to stay at home and unfortunately close schools too. That’s why we took the step that we took. “