Some 2.6 million adult Britons used e-cigarette in 2015, up 24 percent from 2014, according to data from Action on Smoking and Health.
The increase was reportedly driven by a rise in the number of former smokers using the product, with the Smokefree Britain Survey showing that the rate of vaping among former smokers grew by 4.5 percent year-on-year in 2014 and by 6.7 percent in 2015.
E-cigarettes were the fastest growing U.K. supermarket product by volume and value in 2014, with sales rising 50 percent year-on-year to 17.3 million units, according the Nielsen data.
Meanwhile, U.K. sales of traditional nicotine replacement therapy products declined 6.1 percent in 2014.