An estimated 12 percent of people in England had been infected with coronavirus by December last year, up from nine percent in November, according to official antibody data released Tuesday.
One in 10 people in Wales, one in 13 in Northern Ireland and one in 11 in Scotland were also estimated to have caught the virus, according analysis of random blood test results published by the Office for National Statistics (ONS).
Britain is currently gripped by its third and deadliest wave of the virus, blamed on a new strain believed to be highly infectious.
Health chiefs have warned intensive care units risk being overwhelmed by the surge in cases that has already led to the country suffering record numbers of daily deaths.
Overall mortality for the week ending January 8 was 45 percent higher than the five-year average, according to the ONS, although the official statistics body cautioned that the data could be skewed by uneven reporting over the holiday period.
London, which has been hit particularly hard by the latest wave, recorded an 85 percent increase in deaths, compared to the historic average for the same week.
The Medical Research Council at Cambridge University said last week that it believed the proportion of the population who have ever been infected in London was 30 percent.
Britain has recorded almost 90,000 deaths of people testing positive for the disease, one of the worst tolls in the world.
Health minister Matt Hancock, who caught the virus last year, on Tuesday tweeted that he was self-isolating until Sunday after being told by the health service that he may have come into contact with an infected person.
© 2021 AFP