Cafe owner Mike Haggerton pours a cup of Dalreoch white tea at the Habitat Cafe in Aberfeldy, Scotland. [Photo/Agencies]

Once the tea plants have adjusted, Scotland has proved to be an ideal place for them to grow, with its fog, high rainfall, hilly landscape and rich soil.

"It's well accepted among tea experts that the finest teas in Darjeeling or Assam come from areas which are shrouded in clouds for the majority of the year," O'Braan says.

"Also because the plants are in what many would consider to be an unnatural environment, we're producing a certain amount of chemical stress within the leaf. That's responsible for the rather sweet flavor that our tea produces."

The harvest, which is currently beginning and will continue until September, collects the youngest leaves for white tea and rougher leaves for green and black tea.

Dalreoch Estate tea is the first white tea whose leaves are smoke-dried, making it "revolutionary and unique", according to Mariage Freres.

In the Habitat cafe in the village of Amulree close to Dalreoch, owner Mike Haggerton offers sceptical customers free samples of the teas.

"We give a little bit to our clients and the reaction is never been anything other than 'this is incredible'," Haggerton says.

"There is the potential for so much more great tea to come out of Scotland."