The one at Hillcastle in County Wexford did not follow that logic. It sat several miles inland, on a low broad hill in a small townland of the same name, with the nearest coastline roughly five kilometres to the east. Its existence is all the more puzzling because almost nothing of it survives, and even its precise location within the townland is unknown.

The system it belonged to was a chain of over eighty stations, running from Malin Head in Donegal down to Dublin Bay, each communicating with the next by naval signal post, a semaphore-style arrangement of flags and mechanical arms. The Hillcastle station was completed by 1804 and its signal mast erected by 1805, according to the historian Paul Kerrigan. Its neighbours in the chain were a station at Crossfarnoge Point to the south-west, now also demolished, and one at Rosslare Point to the north, where the crew was housed in a Martello tower, the squat circular fortifications built across Ireland and Britain during the same Napoleonic-era invasion scare. That Rosslare site has since been lost entirely to coastal erosion. At Hillcastle, the inland position appears to have been a deliberate choice: by using the modest elevation of the hill, the Board of Ordnance could avoid building a separate station at Carnsore Point, some seven and a half kilometres to the south-south-east. The signal mast was probably raised near the summit, with the crew making use of existing buildings on the Hill Castle estate below, a tower house that had been extended into a courtyard-form country house by the time the Ordnance Survey mapped the area in 1839 to 1840. That map shows no trace of the signal station, suggesting it had already been dismantled, which fits the broader picture: the entire network was wound down by the mid-1810s once the threat of French invasion had passed. The country house itself survived until 1960, when it too was demolished.

Today the site is farmland, defined by the kind of linear field boundaries that replaced the demesne landscaping after the estate broke up. A semi-circular moat, the remnant of the original medieval tower house complex, still arcs around the castle's former footprint. The signal station itself left no visible mark, and its exact position within the townland may never be established with certainty.