The UK government said the new strain could increase the country's R number by 0.4 and suggested that the strain is now behind 59% of new cases in eastern England and 62% of new cases in London.
Denmark, The Netherlands, Germany, Belgium, Austria, Italy, France, Ireland, and Israel are among the nations that have placed restrictions on travel with the UK.
In the meeting, the prime minister was given alarming new evidence on the mutating COVID-19. The possibility of introducing stricter lockdown restrictions as soon as Saturday was also discussed.
Across all of England, people will be advised not to travel. "We're asking everyone in all tiers to stay local. People should carefully consider if they need to travel abroad," Johnson said.
The sudden announcement that London would be put on lockdown resulted in many Londoners trying to escape the city before midnight.
The chaos comes just 10 days before the end of the Brexit transition period when new checks on trade with the EU are set to cause significant disruption at Britain's ports.
The UK government is actively monitoring for social media conspiracies in response to news of a new coronavirus strain. "Public favor [is] eroding day by day," says Dr Stephen Griffin.