For all the tea in Truro: how a Cornish plantation is turning the tables on China

It's shortly after noon and the Tregothnan country estate is bathed in a low blanket of mist.

Leaden skies loom overhead and a steady drizzle of rain makes the surrounding foliage glisten bright green. Occasionally the clouds part. Sunlight streams onto the sodden ground and for a moment you get a brief reminder of what summer is meant to feel like. For holidaymakers heading to this part of Cornwall it's not exactly enticing weather. But Jonathan Jones, the estate's garden director, couldn't be happier. "It's just perfect," he says. "The plants love it."

The plant Mr Jones is specifically talking about is one that is forever associated with England but, until recently, has never been grown here. Tea has always had to be imported, but in the space of just a few years Tregothnan has turned all that on its head. Thanks to Cornwall's warm and wet micro-climate, the estate is currently home to Britain's only commercial tea plantation. The adventure began as a somewhat hare-brained idea with the first harvest producing just 28 grams. Now the estate churns out 10 tons of tea and even exports its produce to India and China.

Cornwall primarily works as a tea-growing location because it rarely has frosts. But this year's wet summer has produced even more perfect growing conditions than usual. "We're almost having two years' worth of growth in one at the moment," says Mr Jones, who learned his craft on trips to Asia. When the sun does come out it's sweltering and humid. The climatic parallels with somewhere like Darjeeling – 6,000ft up compared to Tregothnan's 246ft – are hard to miss.

Since 1900 the average temperature in the UK has risen by about 1C. It may not seem like much but it has significantly lengthened growing seasons and allowed farmers to farm produce that are far more diverse than our historical staples of cereal and potatoes. In Devon, farmers are churning out chillis. Melon and kiwi plantations can be found in the Midlands whilst in Kent we even have walnut groves.

But the idea that tea – a commodity we went to war to obtain and protect – could be grown on British shores seems too good to be true. In some ways it is. There are only a very small number of spots around the UK where tea could thrive.

"Tea plants are really quite fickle," says Mr Jones. "They will grow in a sheltered garden. But there's a difference between having a tea bush which is alive and one that is commercially productive."

The hillsides that Tregothnan lies on are about as perfect as it gets. Sheltered from the Atlantic by the Lizard it has all the benefits of Cornwall's microclimate without being battered by winter storms or salty water, which is disastrous for tea. It is warm, the soil is acidic and, most importantly, there is lots of rain. The estate is owned by the family of Lord Falmouth, one of the oldest aristocratic families in Cornwall. His ancestors travelled far and wide with the British Empire and collected all sorts of exotic plants for the gardens back home. While clearing out a garden shed a few years back workers even came across an original Wardian chest, a wooden hut with glass sides which was invented by the botanist Nathanial Bagshaw Ward and was used by Britain to smuggle tea bushes out of China and into India. Over the years, the gardens back at Tregothnan became famous for exotic flora, particularly its camellias – the same genus of plant as the tea tree. During the late-1990s, while walking through the garden, Mr Jones hit on the idea of growing tea. "I was looking at all these camellias, many of which came from Darjeeling, and they were doing perfectly well," he recalls. "So I thought I'd try to grow tea itself."

A tea bush takes five years to mature to the point where you can harvest it. Tregothnan's first crop was flattened by a storm but eventually the bushes began to sprout enough tender young leaves to be commercially viable. Fortnum and Mason bought up the first batch exclusively but the Tregothnan brand is now stocked at different outlets and is sold online. It is more expensive than standard brands – around 24p a cup, compared to around 6p for a basic supermarket tea. Ironically, Chinese and Japanese drinkers appear to be the biggest buyers of the estate's tea and by next year they expect the overseas market to account for 50 per cent of their sales.

So where next for Britain's first tea plantation? Mr Jones is in talks with a partner about opening a chain of tea rooms on the high street. It would be a bold move but could bring English-grown tea to a much wider audience beyond the enthusiasts and connoisseurs who usually buy their product.

"The tea bar concept has been looked at by a lot of serious companies but no one has made it happen yet," he says. "We think we can. In October Starbucks is planning to open its own tea house in the States.

"It's a disgrace to this country that we haven't beaten them to it. Wouldn't it be fun for the Brits to organise themselves quickly enough to beat Starbucks to it?"