The prime minister will address the nation this afternoon following emergency talks with cabinet ministers amid the emergence of a new strand of coronavirus.
It has been widely reported that Boris Johnson could be set to announce a new, Tier 4, level of restrictions, which will see areas including London and the South East plunge into tighter measures.
It is reported that this may also include travel restrictions for people in these areas, putting into jeopardy trips for those planning to visit family in Norfolk and those leaving the county to see relatives over the Christmas period.
The chief medical officer for England Professor Chris Whitty said the UK had now informed the World Health Organisation that it had concluded the mutant strain could spread more quickly.
"As announced on Monday, the UK has identified a new variant of Covid-19 through Public Health England's genomic surveillance," he said in a statement.
"As a result of the rapid spread of the new variant, preliminary modelling data and rapidly rising incidence rates in the South East, the New and Emerging Respiratory Virus Threats Advisory Group (NERVTAG) now consider that the new strain can spread more quickly.
"We have alerted the World Health Organisation and are continuing to analyse the available data to improve our understanding.
"There is no current evidence to suggest the new strain causes a higher mortality rate or that it affects vaccines and treatments although urgent work is under way to confirm this.
"Given this latest development, it is now more vital than ever that the public continue to take action in their area to reduce transmission."
This afternoon, Boris Johnson chaired a crunch meeting with cabinet ministers, ahead of a 4pm press conference, which he will hold alongside Prof Whitty and the government's chief scientific advisor Sir Patrick Valance.
Saturday's talks came as large parts of the South East were following London and large parts of Essex and Hertfordshire, which entered the toughest Tier 3 restrictions earlier this week.
The latest tiering changes in England - which came into force on Saturday morning at one minute past midnight - mean 38 million people are now living in Tier 3, 68% of the population of England.
Those areas moving into the highest tier are Bedfordshire, Buckinghamshire, Berkshire, Hertfordshire, most of Surrey, Peterborough, Hastings and Rother on the Kent border of East Sussex, and Portsmouth, Gosport and Havant in Hampshire.
Norfolk and Suffolk, however, remained in Tier 2 of the local restrictions, following the tier review on Thursday.
Since then however, figures have shown a steep rise in the number of cases in the county, with some areas of Norfolk approaching 150 cases per 100,000 people.
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