More and more of those buying a few weekends' fishing or shooting, or even an entire estate, are outsiders who have come to the pleasures of Scottish country life as adults. Success at work has brought them into contact with those to the manor born. They have gone shooting or fishing with them as guests and been bitten by the bug. Roddy d'Anyers Willis, who is a director of the Savills office in Brechin, has seen a number of novices become converts. "You're never too old to catch your first fish," he says. "There is nothing a ghillie or stalker enjoys more than a novice, providing the person is a willing listener. But they cannot stand those who think they know it all."
But the sport is only part of the appeal. The biggest attraction, particularly in the Highlands and Islands, is the spectacular landscape, where the scenery changes as often as the weather, where you can stand on a mountain and gaze out to sea, where the air is pure and there is no one to disturb your thoughts. This is what pulls thousands of city-dwellers, not just from Britain, but from the United States and the densely-populated lowlands of Holland, Belgium and north Germany.
Gordon Carruthers epitomises today's estate buyer; he fired his first serious shot at the age of 40. He is most easily described as a wealthy Manchester businessman, but he no longer thinks of himself that way. After 11 years as owner of nearly 8,000 acres 60 miles north of Inverness, he thinks of himself as a Highlander. This is not some vain pretence: Mr Carruthers spends half his year on the Kintradwell Estate and lived there full-time for more than two years.
Brought up in the bustling retail sector of Manchester, Mr Carruthers' only connection to Scotland was through his father's ancestors. His great- grandparents came from the area where he bought the estate, though he says that was just a pleasant coincidence. Having spent the first 20 years of his adult life carving out a successful career, he decided to take a step back. "There comes a point in your life when you start to think about the way you live," he says. "I felt Scotland was a place I might like to be.
"It's so empty compared with the south. The sense of freedom you get is quite marked. The difference in the quality of the air, the openness, the big skies - it gives you a tremendous feeling of physical well-being."
Kintradwell is a classic sporting estate with red deer stalking, a pheasant and grouse shoot, a small salmon river and miles of beautiful hills and empty beaches. There is a main house with six bedrooms, three bathrooms and the all-important Aga, plus six cottages, mainly occupied by estate workers.
The Carruthers are leaving Kintradwell, now that their three children have grown up. They are selling the estate, with an asking price of pounds 1.5m, and looking to buy something more modest. "It's a wonderful feeling to go somewhere and stand on a hill and have a sense of belonging to that particular place," he says. "But it's a big responsibility. You don't own it; you're just the keeper."
Colin Strang Steel of Knight Frank & Rutley in Edinburgh is selling the Kintradwell Estate. He says it is the sense of belonging, rather than just extra money, which separates those who buy an estate from those who rent or buy a few weekends' sport. "People get to know a place and they fall in love with it," he says. "It is the total opposite of what they are doing in the rest of their lives."
It is easy to imagine falling in love with the Kintradwell Estate, one of the most spectacular properties currently on the market. For the price of a penthouse in Chelsea, the new owner will buy a whole new way of life.
Savills 01356 622187; Knight Frank & Rutley 0131 2258171