According to a U.K. public health paper published last year, the e-cigarette market was worth £193 million in 2013 and is expected to be worth £340 million in 2015. Globally, the market is expected to be worth $3.5 billion in 2015, according to Bonnie Herzog, Wells Fargo Securities' senior tobacco and beverage analyst.
Read MoreUK consumers may be happy but they still won't spend
"E-cigarettes initially were limited to online channels, however growing availability is increasing consumer accessibility," said Mintel's Khanom. "In 2014 alone, e-cigarettes became available in newsagents, supermarkets as well as specialised stores. As such, the segment is likely to show continued growth."
E-cigarettes take the form of a battery operated device that aims to stimulate cigarettes.
While the risks of e-cigarettes are intensely debated, they are generally viewed as a safer alternative to cigarettes. Although they deliver a nicotine-laced vapour to smokers they do not contain the harmful chemicals contained in tobacco.
This may help explain the popularity of e-cigarettes, experts said.
"About two-thirds of smokers say that they want to give up smoking, but they continue because they are addicted to the nicotine and so find it hard to quit," Amanda Sandford, research manager at Action on Smoking and Health (ASH), a public health charity, told CNBC.
"These products provide the nicotine that smokers crave but in a safer way, so they are not getting all the harms from the tobacco smoke and that seems to suit a lot of people."