In 1855 Edwin Wyndham-Quin, the 3rd Earl of Dunraven and Mount-Earl, bought Garinish from the Bland family of Derryquin Castle. The earl was 43 years old, in the prime of his Victorian wealth, and what he wanted was a holiday house. He hired the architect James Franklin Fuller, who designed half the country houses of Kerry, and the contractor Denis William Murphy, father of the businessman William Martin Murphy who would later run Dublin's tram system. Together they built Garinish Lodge - a substantial residence in the most beautiful place an earl could find. The garden came with the house. It was, at first, the usual mix of clipped lawns and gravel walks that a Victorian estate expected. That changed when the next earl took over.

From 1900 onwards Windham Wyndham-Quin, the 4th Earl, turned Garinish into something more interesting. The Gulf Stream warms the south-west of Ireland enough that exotic plants can survive winters they would not endure further inland or further north. The earl filled the island with tree ferns - the great prehistoric-looking fronds that thrive in moist coastal air - and Cordyline australis, the so-called cabbage trees of New Zealand, with their spiky crowns and pale stems. He created what gardeners called a wild subtropical garden: not the geometric formality of Versailles but something looser, designed to look as though the plants had chosen the island themselves. Much of that planting is still alive today. Tree ferns are slow growers and long livers.

In September 1922, during the Irish Civil War, Garinish Lodge burned. Anti-Treaty forces torched dozens of grand houses across Ireland in those months - symbols of the old Anglo-Irish order, easy to justify destroying. The fire took the lodge, but not the garden. When Lord Dunraven died in 1926 at the age of 85, the island passed to his only surviving child, Lady Aileen May Wyndham-Quin, who held it for the next 36 years. Around 1950 Reginald Browne and his wife bought Garinish and set about rescuing what had been neglected. They rebuilt the lodge, replanted what had been lost, and let the tree ferns spread back through the understorey. Their sons continued the work. By the time the family sold, the garden was back.

Since the 1990s Garinish has been owned by Jacqui Safra, a Swiss investor descended from the Syrian Jewish banking dynasty that built one of the world's quietest financial fortunes. The Safras came from Aleppo, established banks in Beirut and Brazil and Geneva, and accumulated the kind of generational wealth that buys things like private islands off the coast of Ireland. Jacqui Safra produced a few films in the 1990s, including Woody Allen's Shadows and Fog, and otherwise kept a low profile. Garinish stays a working private estate. You cannot land there. The garden is closed. What you can do is rent a kayak or a small boat from Sneem or Parknasilla and paddle past, looking up at the tree ferns and the rebuilt lodge, and imagine the earl who started all this 170 years ago.

There is another Garinish - a more famous one - in Bantry Bay, run by the Office of Public Works and open to anyone with a ferry ticket. This is not that island. This Garinish is smaller, more secluded, and visible only from outside its boundary. The contrast is itself interesting. Ireland has very few private islands left in active use. Most have been turned into nature reserves or holiday rentals or simply abandoned to the sheep. Garinish remains a working garden, tended by a wealthy owner for his own pleasure, in a tradition that runs straight back to the Victorian earl who planted the first fern.