Little Cumbrae, which lies in the Firth of Clyde off the north Ayrshire coast, has been put on the market for offers above £3m.
Rich property buyers looking for a retreat from the rat race are unlikely to find anything more exclusive than the 684-acre island 23 miles from Glasgow.
A London estate agent is offering prospective buyers the chance to buy the ultimate status symbol complete with its own 12-bedroom Victorian mansion and 13th-century castle.
The island, which lies in the shadow of Great Cumbrae and is a 10-minute boat ride from Largs, also boasts a centrally situated lighthouse with three keepers' cottages, built by Robert Stevenson, which replaced the open fire beacon.
The current owner, Stephen Worrallo, a businessman who bought the island two years ago, has decided to put it on the market with the aim of selling it to either somebody looking for a secluded retreat or someone wanting to explore the development and tourist potential of the island.
Glenn Hickman, spokesman for the Mayfair-based HHL Humberts Leisure, the agent dealing with the sale, said Little Cumbrae offered a rare opportunity as British islands were very rarely sold on the open market. "We don't get private islands coming up for sale very often," he said.
"We have had quite a lot of interest already from private individuals, who just want a hideaway place with a bit of privacy, and from commercial developers and leisure operators interested in the potential the island offers. Any development would have to be sensitively undertaken because of the quality of the land, the wildlife and suchlike but there is still plenty of scope.
"Little Cumbrae is particularly unusual because it is so close to civilisation, being just six miles from Largs and 23 miles from Glasgow airport, but at the same time it can be completely separate." The championship golf courses of Turnberry, Royal Troon and Prestwick are near by.
Rich in history and ecology, the island, which lies within the Gulf Stream and is a natural gateway to the magnificent sailing waters of the west coast of Scotland, is home to a great diversity of rare and varied flora and fauna. A recent survey by the RSPB listed 57 species of birds breeding on the island.
Besides the seabird populations and thousands of rabbits, the only permanent inhabitants are Alistair and Bonnie Davidson. They moved there three years ago as resident caretakers of the island. Although they have a clear view of the mainland, the couple, who have to be self-sufficient, importing supplies and heating oil, admit that during bad weather they might as well be thousands of miles away.
The island, which is just under a mile at its widest point and once boasted a population of 54, has no telephone line after a trawler snagged it a few years ago, making communication with the mainland solely reliant on wireless technology.
However, there is plenty of accommodation on the island, which was once the site of a religious cell founded by Saint Veya, a seventh-century nun, and has historical links to Robert the Bruce in the 13th century.
Across the island there are many historic buildings, including the 13th-century castle keep, a number of steadings and a boathouse, jetty and workshops.