The Kent coronavirus strain has mutated which could make it partially resistant to vaccines.
The E484K mutation, which occurs on the spike protein of the virus, is the same change as has been seen in the South African and Brazilian variants that have made them partially resistant to immune response and caused international concern.
Professor Calum Semple, a member of the Scientific Advisory Group for Emergencies (Sage), told BBC radio: "The mutation of most concern, which we call E484K, has also occurred spontaneously in the new Kent strain in parts of the country too."
He was referring to the UK variant, which scientists call B.1.1.7 and which was first detected in Kent last autumn - reports Mirror Online.
The Government is so worried about the South African strain that it has launched a door-to-door Covid-19 testing blitz in eight postcodes where it has been detected recently.
The fact that the E484K mutation had occurred spontaneously in Britain had already been reported in a technical briefing published by Public Health England, but this had not been widely noticed outside of scientific circles.
A summary of the briefing said: "A limited number of B.1.1.7 VOC (variant of concern) ... genomes with E484K mutation have been detected."
Professor Semple, a University of Liverpool expert on severe virus disease outbreaks, was speaking in the context of an interview about the issue of how to suppress the South African variant.
It came as a door-to-door and mobile testing blitz began in eight areas of England to help identify cases of the South African variant.
The plans are part of urgent efforts to swab 80,000 people, who are living in areas where cases of the highly-infectious variant have been found, in an attempt to halt the spread of the strain.
Eleven cases of the variant have been identified over the last five or six days in people who have no links to travel - suggesting it may be spreading in communities, including in Southport.
Professor Semple told BBC Radio 4's Today programme: "It's incredibly important to snuff it out where you can and seek it out where you can and use that time of suppression to maximise vaccination within the population.
"But there is an inevitability with these viruses, particularly with these mutations that we're now seeing arising spontaneously in Brazil and in the South African strain."
Find your nearest vaccination centre by entering your postcode below
He said it is still uncertain how significant the new strain is.
He said: "The huge effort to test and trace and observe for reinfections and readmissions is incredibly important to help us understand what is going on here, but the honest answer is that we really just don't know about the clinical importance of this.
"But certainly we don't want a virus like this spreading throughout our community and taking advantage of the lack of immunity that we currently have."
Professor Semple said that while it is important to restrict the movement of people as much as possible, it is not practical to close the UK's borders completely.
He said: "You can't do it altogether when you have got a country that is dependent on imports for food and other essential processes. It is just not possible."
He went on to make the point about the spontaneous appearance of E484K in the Kent variant.
The name E484K, in layman's terms, is like map coordinates.
The number 484 is the exact location of the mutation, the letter E is the amino acid that it was originally and the letter K is the amino acid that it has mutated to.
