Like many of Britain’s old landowning families, the marquess’s family has been through decades of retrenchment as a result of inheritance taxes. It lost the family seat, Culzean Castle, to the National Trust in 1945, and in 2010 the current marquess decided to part with Ailsa Craig, posting an initial price of $4 million. That figure was later cut to $2.4 million, and as the waters of the Firth of Clyde have lapped at Ailsa Craig’s rocky shore each day, little has changed in the intervening years. The island remains misty, monumental and for sale.

Image Credit... The New York Times

When Keats first saw the island soaring 1,100 feet into the sky off Scotland’s west coast in 1818, he repaired to a mainland inn and wrote a sonnet by candlelight describing it as a “craggy ocean-pyramid,” summoned from the deep by some mythic power, and attended for eternity by eagles and whales. Nearly 200 years later, with Scotland approaching a referendum on independence from Britain next September, it remains an icon in the country’s national consciousness, redolent of the rugged, stand-alone character many Scots pride as their birthright.

Earlier this month, approaching across 10 miles of shimmering open sea aboard his 35-foot lobster boat, the M.V. Glorious, the skipper, Mark McCrindle, broke the silence of his cramped wheelhouse to say that in 30 years of plying the waters from the nearby port of Girvan, he had rarely seen it looking more majestic. “Aye,” he said, “she’s a beauty.” Would he like to own it? “Twenty thousand pounds is all I’d pay,” he said, quickly adding, “What would I do with it?”

Finding a buyer will require more than the poetic flights of Keats, or “the dreams” the 57-year-old marquess says he would be selling to anyone whose fancy runs to an island that has no modern conveniences, no active forms of employment since the quarrying ended in 1969, and only one habitable structure among the rusting, roofless ruins of the quarters once used by men working in the lighthouse or the quarries.

Over the centuries, the island’s 220 acres, much of it in the form of precipitous crags and thick uphill reaches of bracken, have provided Scots, and sometimes their enemies, with an ocean fortress. Barely three-quarters of a mile from tip to tip, the island has served as a redoubt for repelling Spanish invaders, a sanctuary for pirates and, for the last 25 years, a preservation area for tens of thousands of breeding seabirds, especially gannets and puffins.