Britain is a nation of tea-drinkers - we collectively drink around 65 million cups of the stuff every single day of the year. But untl fairly recently, not much of it was served cold.

Cold-brew tea, however, is slowly seeping its way across Britain. Made by adding tea leaves to cold water and refrigerating it, usually overnight, it is said by tea aficionados to showcase the delicate favours of tea more effectively than hot water from the kettle. Cafes around the country are adding cold-brew teas to their menus quicker than you can say "A cup of builder's please", while various street food trucks in London, from Hotbox Brew to Good and Proper Tea, are spreading the cold brew message across London's hipster hotspots. The capital even now has its very own cold-brew pop-up, Kenko Tea Bar, in Old Street.

"When creating hot brew tea, you run the risk of burning the tea leaves, which can result in a bitter taste. The cold brew process slowly draws out the flavour of the tea and the leaves remain alive, giving a fresh and vibrant flavour," explains Limau Chen, Kenko's co-founder. "Cold-brew is an extremely popular drink in Far East Asia, and has recently also become a trend in the States and Canada as people are becoming aware of the health benefits: cold brew contains significantly lower levels of caffeine than traditionally hot brewed tea, and Kenko Cold Brew Teas contain more antioxidants."

But don't make the mistake of thinking that this is simply a trendy new name for that American favourite, iced tea. Kasim Ali, director of the Waterloo tea houses in Wales, which have been serving cold brews for six years, says: "Iced tea is essentially just hot tea poured over ice. It's good from a commercial point of view because it's easy to make, but effectively you're overbrewing the tea, because you put double the normal amount of tea in. The end result is very bitter, which is why you get extra flavours like lemon added.

"When we make cold brew, we only add about fifty per cent more tea than if you were making a normal cup. It really shows off the nuances of flavour."

So if cold brew is this delicious, why has the trend only now starting to gain traction in the UK? Rob Comins, of Comins Tea House in Sturminster Newton, Dorset, says that although the British public has been become more experimental with food and drink in recent years, convincing people to deviate from their beloved hot cuppa in the morning is a tricky task. "For a long time the British taste has been for strong black teas which taste awful cold. Therefore the thought of buying one that is deliberately served cold was not very appealing," he says. "We know from reactions in the tea house and at food shows that breaking this perception is difficult, but once they've tried cold brew, very few people react badly." The trend for cold brew coffee, which is made in a similar way, has also normalised the idea of serving traditionally hot drinks from the fridge instead.

So what teas respond best to the cold brew treatment? Certainly not your bog-standard English breakfast blend. The Bluebird Tea Co, a Brighton-based online tea emporium, recommends using green, "because the slow brewing process brings out the more fruity flavours". Delicate teas such as oolongs and white teas are also popular choices. If you plan to try cold-brewing at home, Limau Chen recommends an average steeping time of eight hours in order to extract the maximum flavour, but warns that some teas can start to taste bitter much earlier than this. "Finding the perfect steeping time for you may require a little experimentation and patience," she says.

If one factor will hold back the cold brew revolution, it is probably the British weather. When it's sunny outside, says Kasim, cold-brewed teas served with fruit, such as white tea with tangerine and green tea with lemongrass, "fly" out of his cafes. But we all know that it's cold, only a steaming cup of char will do. So perhaps it's not time to throw away your Earl Grey quite yet.

(China Daily 04/04/2015 page9)