While chemistry might not have been everybody's cup of tea in school, it's proving to be everybody's cup of cocktail these days. Enter the brilliantly blue butterfly pea flower from Thailand with its chameleon-like colour-changing properties, turning purple when it comes in contact with lime juice.

"This unique flower makes it the perfect addition to a good-looking drink without using any artificial colour," says Ami Shroff, mixologist at London Taxi, one of the latest bars to have caught on this trend that first saw traction six months ago.