We know this much, and not a great deal more. It dates, by attribution, to the 16th or 17th century, and it has left behind no standing walls, no mapped footprint, no local legend attached to a particular field or lane. Its existence rests almost entirely on a single cartographic source, and even that source cannot pin it down with any precision.

The evidence comes from the Down Survey, the extraordinary mapping project carried out between 1655 and 1656 under the direction of Sir William Petty. Commissioned by the Cromwellian administration to document forfeited Irish lands following the upheavals of the 1640s, the Down Survey produced detailed parish and barony maps across much of the country, recording settlements, townlands, and landholdings at a scale and ambition that had no real precedent in Ireland at the time. It is on one of these maps, covering the area around Portraine, that a dwelling is recorded. Geraldine Stout, who compiled this record in 2011, notes that the feature is not precisely located, which is to say the map marks something in this general area, but the survey's conventions and the passage of nearly four centuries make it impossible to say exactly where.

There is, in practical terms, nothing to see at Balleally West that can be directly connected to this record. The value of a site like this lies less in a visit and more in what the uncertainty itself suggests, namely that the landscape here was inhabited and documented at a time of considerable upheaval in Irish land ownership, and that even a thorough surveying effort left ambiguities that have never been resolved. If you are in the area, Balleally West sits close to the Portraine peninsula, a quiet stretch of north Dublin coastline, and the broader townland can be explored on foot. Those with an interest in early modern cartography might find it worthwhile to examine digitised versions of the Down Survey maps, several of which are held and made accessible through institutions such as Trinity College Dublin, where Petty's original work can be studied in considerably more detail than any field visit would allow.