Local produce and holiday rentals are part of a reinvention that is bearing fruit for the Tregothnan Estate, says Rhiannon Batten

You don't have to go far to find peace. Turn left at Truro's Tesco supermarket, take another couple of turns, follow a twisty country lane for a mile and a half, open and close some farm gates, bump down a narrow bramble-lined track and you're at one of the quietest spots in England: Pencreek Cottage.

Arriving at dusk, the setting felt magically calm. Steps away from a creek off the river Fal, the landscape had taken on an eerie hush in the fading light. Ahead, I could make out a boat tethered to the opposite bank. To either side were shadowy orchards and paddocks. The only sounds were those of distant owls and a family of ducks, suddenly skittering across the water, unsettled by my footsteps scuffling on the cottage's gravel terrace.

Pencreek is owned by the largest private estate in Cornwall, Tregothnan – the seat of Lord Falmouth – and opened last winter as one of the first of the estate's new collection of "Wild Escapes" holiday cottages. For guests, the concept offers a temporary diversion from hectic day-to-day life (albeit one that comes with king-size beds and high-spec kitchens). And for the estate, it's a means of making disused estate cottages pay their way when tenants decide not to renew a tenancy. This usually happens, the estate told me, with elderly tenants or new families who move on when the isolation becomes an inconvenience.

Such reinvention is second nature at Tregothnan, which dates back to 1335. The estate was the first – and remains the only – commercial cultivator of tea in England, a project instigated when Tregothnan's incumbent garden director, Jonathon Jones, deduced that if his camellias flourished, tea might too.

Tregothnan also sells Cornish flowers, tea-flavoured chocolates and the only manuka honey produced outside New Zealand. Other plans this year include a scheme to re-establish the most southerly asparagus patch in the UK, and the recent opening of a restaurant and tea bar in Tolverne.

"It's easy to assume that diversification and sustainability are modern trends, but any successful working estate will tell you that they are integral to their survival," explained Jonathon, over a cup of Tregothnan tea at the estate's headquarters, just across the water from Pencreek Cottage. "The number of large country estates now in the hands of organisations such as the National Trust and English Heritage, or sold off for private development, are testament to the challenges involved in running and maintaining them."

For Tregothnan, one of the biggest challenges is getting some extremely wild Wild Escapes cottages on to the market. At Kynance Cove, two miles north of Britain's most southerly point, Tregothnan owns two former fishermen's cottages. It hopes to have these ready to rent next year, but there's much work to be done.

The project's manager, Lucy Simpson, showed me around the site on a blustery day. There's no road access to the cottages, which sit opposite a National Trust café, so Lucy and I scrambled down a narrow track instead. In front of us was a tumult of sharp, black rocks hurled around the shoreline and a barrage of almighty waves pummelling what little beach was left at high tide. Up above were wide grassy slopes perfect for sitting and admiring the water on more clement days.

Uninhabited for several years now, the cottages are currently watertight but otherwise derelict – blank canvases waiting to be brought back to life. All that was on show when I visited was the site's potential. The larger cottage sits so close to the shore that, from an upstairs window, all signs of land are obliterated by waves. As of next year, whoever rents it will have to contend with their share of curious passers-by, placed as it is between the beach and the café. Standing there on a wild and windy day, though, it was easy to get a sense of the solitude that will make it a one-of-a-kind escape when the crowds have gone home at the end of the day and there are just four walls separating would-be guests from Kynance's dramatic, untamed geography and cresting waves.

Before then comes the small matter of renovation. Embracing the site's logistical challenges may be problematic for the estate but it will also be what makes the cottages magical. The lack of mains electricity or water at the site offers an opportunity to introduce reed beds, solar panels and peat toilets. The lack of road access, TV and internet might also prove attractive to some potential guests.

"It's such a sensitive site," Jonathon explained later that day. "Kynance is an iconic part of Cornwall, part of an area of outstanding natural beauty, and I don't think I'd be wrong in saying those cottages are the most enquired about properties in Cornwall. That puts a responsibility on us to develop them in the best way that we can. The National Trust has done a really good job in making the buildings they have at Kynance as sensitive to the environment as possible. We want to build on that and make our cottages even better."

In the meantime, Jonathon is getting to grips with a fruitier challenge back at Pencreek, the most luxurious cottage on Tregothnan's books. Though the design veers towards the comfortably suburban with its silk-effect throws, glass dining table and chrome bedstead, more impressive additions include a wood-burning stove, Wi-Fi, and a roll-top bath by an upstairs window complete with waterside views.

The proximity to nature is the real draw here. On one side of the cottage a grove of slender, lichen-covered trees stand to attention like a ghostly, jade-coloured battalion. Walk among them and they appear so fragile it's hard to believe they have withstood a winter but, in fact, they've been on the site for 300 years. They are also part of Tregothnan's latest mission.

The trees are kea (pronounced key) plums, explained Jonathon. Found only in this valley, the gooseberry-sized fruit they produce come in four varieties – black, red, grey and crystal – but no one knows exactly how or when they arrived.

"Three hundred years ago the Portuguese were trading up and down the Fal river and one theory goes that they brought these plums with them and grew them," Jonathon explained. "The other theory is that they spontaneously developed and that the locals kept selecting the ones they liked."

What is known is that they've survived in this location because of its geography. "It's a sea creek. Being five or six miles inland it's very sheltered but it's also, effectively, seafront. There was no road here until 1938 so the old boys used to pull up in boats and shake them straight in."

"The locals say you have to shake them three times," he added. "The first to get rid of the maggots, the second for the jam pot and the third for eating." There's logic there though: it's more efficient to harvest them this way because it's hard to hand-pick such small fruit.

Tregothnan is hoping that guests staying at Pencreek Cottage will help to spark interest in the adjacent orchards and that by selling kea plum jam, katsup (ketchup made from plums) and ice cream in the estate's shop it might eventually help to save the species. They're also applying to the European Union to get the kea plum registered for protected status, alongside Melton Mowbray pork pies.

"We've got 20 acres of kea plum orchards and around six are being harvested, giving us five or six tonnes of fruit a year. If we could produce 10 tonnes we would be commercially viable," said Jonathon. "We're trying to find a market for the plums; if there's a value on them, they'll survive".

Travel essentials: Cornwall

Getting there

* The closest train station for Tregothnan is Truro (08457 48 49 50; nationalrail.co.uk).

Staying & visiting there

* Pencreek Cottage, Pencreek, Coombe, near Truro, Cornwall TR3 6AR (01872 520000; tregothnan.co.uk). Sleeps two. Rental starts at £359 per week.

* Smugglers Restaurant and Tea Bar, Tolverne (01872 580309; tregothnan.co.uk).

More information

* Cornwall Tourist Board: 01872 322900; visitcornwall.com