The 1914 edition of the Ordnance Survey six-inch map records it clearly enough: an oval shape, roughly thirty metres along its longer axis, sitting close to the centre of the lake. It is the kind of detail that cartographers do not invent. And yet, when surveyors went looking for it, the lake had become something else entirely, a swamp dense with man-sized reeds and sally trees, the water table risen or the vegetation thickened to the point where any solid ground, if it still existed, refused to announce itself. A thorough search found nothing.

What the map was likely recording is a crannog, a type of artificial or partially artificial island constructed in lakes and wetlands across Ireland and Scotland from the Bronze Age onward, often used as a defended homestead or place of refuge. They were built from timber, peat, stone, and brushwood, and many survive as low wooded humps just above the waterline. The Lehery example, if it survives at all beneath the reed beds, would have measured a modest but workable thirty metres by twenty-five. Its disappearance from view is not entirely unusual; crannogs in shallow, silting lakes can become effectively invisible as the surrounding landscape closes in over centuries. A second possible crannog has been recorded roughly seventy-five metres to the south-south-east, which at least suggests this was not a stretch of water people ignored in earlier times.