Somewhere on the cliffs above Bunmahon Bay, Co. Waterford, a signal tower once stood that has since vanished so completely that nobody is entirely certain where it was. It does not appear on the Ordnance Survey six-inch maps surveyed between 1839 and 1841, meaning it had already been torn down before the first systematic mapping of the Irish countryside was even underway. The most reliable clue to its location comes from Larkin's 1818 map of County Waterford, which marks it simply as 'telegraph', in a position that corresponds roughly to an orphaned trigonometry point on the later Ordnance Survey sheets; a surveying marker apparently left stranded after the structure it had been associated with was gone. The probable site sits near a narrow coastal promontory called Slippery Island, jutting into the bay, and close to an earlier coastal promontory fort, a type of defended headland enclosed by earthen banks or ditches that was in use long before any British military planner arrived on the scene.

The tower was part of a chain of over eighty signal stations built by the British Board of Ordnance in the early nineteenth century, strung clockwise around the entire Irish coastline from Dublin Bay to Malin Head in Donegal, with the explicit purpose of giving early warning of a French invasion fleet. A signal mast was in place at Ballynarrid by 1804, and the tower itself was completed the following year. Its nearest neighbours in the chain were at Ballyvoyle Head, roughly 8.2 kilometres to the west-south-west, and at Islandikane South, around 11 kilometres to the east; both are also demolished. What makes the Waterford towers peculiar within the broader network is how quickly they disappeared. Five of the six built in the county around 1804 to 1805 were gone before the Ordnance Survey arrived, a rate of demolition markedly higher than elsewhere along the coast. A partial explanation survives in a letter from 1811, written by a Mr Pope, Waterford agent of the London Assurance Company, who raised the alarm that derelict signal towers along the Waterford coast were being mistaken for lighthouses by sailors in poor visibility, particularly for the lighthouse at Hook Head in Wexford. He held these confusions responsible for a series of shipwrecks near Tramore around 1810. His concerns appear to have prompted at least one demolition, probably at Brownstown Head, before the end of 1811, and it is plausible that other Waterford towers were cleared for the same reason around that time. The system as a whole was abandoned by the mid-1810s, once the threat of French invasion had receded and the structures had outlived the emergency that conjured them into existence.