On 4 July 1884 the naturalist John Harvie Brown stepped ashore on Priest Island and found something that ought not to have been there: a near-perfect circle of nine stones lying flat, smaller ends inward, the whole thing flush with the short green sward. The stones, he wrote, had a 'highly polished surface... as if done by human hands (or feet).' He sketched it - a feature about four metres across - and made a careful note of where it sat. When he returned for his second visit, the stones were gone. Not weathered, not collapsed - removed. On his fourth visit in 1903 he searched the surrounding ground, collected nine stones he was fairly sure were the originals, and laid them out again in the same plan. He also noted at least two other stone circles nearby, smaller and less perfectly built. The 1794 Statistical Account spoke of a 'large cove on the south side of Priest Island, said to have been the alternative home of a Popish priest' - probably one of the island's caves, which still survive, one of them subdivided by a drystone wall from floor to ceiling.

The Gazetteer for Scotland records Priest Island as an early Christian retreat - a piece of land remote enough that a hermit who wanted to be left alone with God could mostly count on the weather to do it for him. The island's Gaelic name, Eilean a' Chleirich, means the cleric's island, and the cove with the drystone wall may have been his cell. Centuries later the place attracted another solitary: Frank Fraser Darling, the pioneering ecologist who lived on the island for a stretch in the twentieth century while doing the kind of patient observational work that helped found British nature writing. Fraser Darling found a midden in one of the caves - probably the priest's - though no trace of it survives now. The history of Priest Island is a string of people who deliberately chose to be hard to find.

Today the Royal Society for the Protection of Birds owns and manages Priest Island as a nature reserve. It is a Site of Special Scientific Interest and a Special Protection Area, and it holds one of the largest colonies of European storm petrels - Hydrobates pelagicus - in the United Kingdom. Salt spray and bird guano enrich the soil enough to support unusually species-rich maritime heath and cliff communities around the coast, and a small amount of woodland clings to the more sheltered ground. Pygmy shrews, otters and grey seals share the rocks with the seabirds. In the summer of 1960, pupils and teachers from Whitgift School in South Croydon spent two weeks here with formal permission to ring birds - hauling a quarter of a ton of supplies on a trek cart pulled all the way from Garve Station. They netted storm petrels at night and shags on the cliffs by day. It is hard to imagine the modern logistics of that, harder still to picture the children doing it. But Priest Island has always rewarded patience and punished anyone who came expecting comfort.