Johnny Sandelson is a man in a hurry, even on holiday. Right now, he is keen to show off his vegetable patch. “Keep up, keep up,” he insists, striding up steep stone steps that rise, two storeys high, from the entrance of his sumptuous holiday home to the parking area at the top.

Actually, he’s keen to show off everything, and why not? Pencalenick House is a modern home of glass, stone and timber, set in deep countryside, with views across a creek to the old Cornish town of Fowey. Hidden within a knot of narrow lanes in what the brochures call “du Maurier country”, this is a place to escape to, where the most intrusive sounds are those of water lapping on the private beach and the chef chopping up something for lunch.

If it feels more like a luxury hotel, that’s only to be expected, given that his business is hotels. Sandelson, 40 owns six in central London – or, rather, co-owns them with hundreds of private investors. He’s the man behind GuestInvest, a scheme whereby investors buy a single hotel room, managed and maintained by the hotel, and in return receive 52 days’ use a year, half of the net room revenue and any rise in price if they decide to sell. Rooms in his newest venture, the Jones, in Bays-water, cost from £317,000. At Blakes, in west London, part of the collection from next year, prices will start at £1m.

Pencalenick is equally upmarket. This is not your average West Country bolt hole. For a start, it has a permanent staff of six, including a full-time chef, lured from one of Fowey’s top restaurants, and a small flotilla of boats, with skipper: a 50ft motor launch, a dinghy and an RIB (rigid inflatable boat).

Then there’s the art. The house is pretty minimalist, with white walls, subtle lighting and plain elm floor-boards – but, thanks to Sandelson’s brother Robert, who owns a Cork Street gallery, it doesn’t feel dull, even if you don’t happen to be staring out of the double-height glass wall of the living room at the wind in the trees or the boats on the creek. There is a painting of the brothers on Primrose Hill by Nicho-las Hely Hutchinson, and a Terry Frost hangs in one of the children’s rooms. Representing Cornwall are works by Patrick Heron and Ben Nicholson.

A London interior designer ensured that every tap, tile, window opening, reading lamp and door is both functional and unobtrusively “right”. Sandelson helps keep it that way through constant vigilance. When a small and muddy visiting child climbs on a white-linen-covered table, he hardly has to raise his voice for him to vanish and a grown-up rush in to wipe it down. The two labradors are confined to the “mud room”, which is a lot cleaner than most nearby kitchens after a week of heavy rain.

Sandelson didn’t get where he is by taking it easy. The son of a stockbroker with a portfolio of commercial property, he went from a history degree at the University of Buckingham to a job with a firm of chartered surveyors in 1990, a time when the market was turning sharply from boom to bust. “I saw the way the banks behaved, and how fear came strongly into a marketplace that had been governed by greed,” he says. “The same dynamics are at work now.”

In 1992, Sandelson and a partner bought a two-bedroom flat in Fulham, west London, with money borrowed from family and friends. They paid £119,000, spent about £25,000 doing it up and sold it nine months later for £175,000. Emboldened by their success, they began buying similar properties two or three at a time, then doing them up, before moving briefly to mews houses. In 1998, when margins became tighter, they changed tack again, buying up plots with complicated planning issues.

It was while working on a development in Cornwall, selling serviced flats off-plan, that Sandelson realised there was “an extraordinary demand in the UK for high-quality property assets, hassle-free and with rental income” – which led him to set up GuestInvest in 2004. “It sounds a bit grandiose, but I have created a new asset class,” he says.

He was tipped off by a local agent about the six-acre plot near Fowey, which he bought in 2000 after a fierce bidding war. “It had consent for a tiny house, but, because of the sheltered position, I knew that if we did something contemporary with wood and stone, it would be fairly invisible and we could get more,” he says. Obtaining planning consent took years, but the house, designed by the London-based architect Seth Stein and completed in 2005, has won a local building award and was shortlisted for this year’s Riba awards.

Sandelson and his wife, Mary Alex-ander, who works in publishing, are both tall, and this is a house for tall people: the day-bed-style sofas, from Caravane, in Paris, are huge; the sinks in the bathroom are set high. “Some people have to stand on tiptoe to brush their teeth,” he says with glee.

The couple, who have three children – Jacob, 12, Florence, 10, and Sacha, 4 – and live in a small house near Oxford, use the house themselves in August, at Easter and in many half-terms, but let it out for a third of the year. The price is £2,500 a day, although that is for 16 and includes “food, boat, staff, wine, everything”. Apart from the seven bedrooms, you get the run of the office, the treatment room, the roof terrace and the family room, with table football.

Despite gloomy headlines about the property market, Sandelson remains upbeat. “There’s an undersupply of quality hotels in London and, as the pound weakens, they will be more attractive to foreigners,” he says. “Sales are slower than last year, but still significant. It’s too early to tell whether we are immune to the global credit crunch, but a correction is a chance to buy new things.” And perhaps a chance to slow down a bit, too. + www.guestinvest.com, www.pencalenickhouse.com

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