You don't need to be mad, but it helps

Nutter needed: another of Britain's tiny islands is up for sale. Only eccentrics need apply. Only eccentrics will apply, for there is something about islands that appears to attract them.

As their Inner Hebridean haven goes on the market again, all the 60 residents of Eigg can do is pray for a benign and well-intentioned wealthy madman. For 15 months, they have been owned by a German artist, Marlin Eckhard Maruma. The 43-year-old, chain-smoking, beret-wearing professor (self- styled) spouts New Age philosophies and creates paintings by burning the canvas. His name is said to have come to him as a sign, apparently written in puddles of water.

The islanders rarely saw him. Nevertheless, they were well disposed to him, until he sold all their cows (except one, Barney). The previous owner, Keith Schellenberg, was none too popular, either. A former British bobsleigh captain, he reciprocated the feelings of his tenants, describing them as "drunken, ungrateful, lawless, barmy revolutionaries".

Unusual behaviour is a badge of honour among island-owners. Even Richard Branson, who owns Necker in the Caribbean, is not what you would call conventional. And Marlon Brando, who bought the Tahitian island of Tetiaroa nearly 30 years ago, was probably more at home when he went native in Apocalypse Now.

Then there are the Barclay brothers, millionaire twins with an almost pathological desire for secrecy, particularly over their life on the Channel island of Brecqhou where they are building a mock-Gothic mansion. The reclusive duo are going to court to win independence from the neighbouring Crown-owned isle of Sark.

They are not, however, as unique as they might seem. In 1985, plucky Tom McLean unsuccessfully lay stake to Rockall by landing on the tiny North Atlantic outcrop, hoisting a Union flag and pitching his tent for 40 days. Today there are nearly 3,000 privately owned islands in the world.

So what's the fascination? For some, perhaps, ownership is a mark of their own emotional isolation. For them, Paul Simon famously sang: "I am a rock, I am an i-i-island." Oliver James, a clinical psychologist, says, however, that the desire to get away from overcrowded mainland Britain is understandable.

But he adds: "You can perfectly well do that on the mainland. So you might want an island if you're extremely paranoid or have reason to be anxious that people are after you."

John Donne, however, recognised that there is no real escape, that even the wealthy, for all their money, must, eventually, make peace with the mainland. "No man," said the 17th-century poet, "is an island. Every man is a piece of the continent". Try telling that to the Barclay brothers.