The pieces are chamfered, their surfaces tooled, and set into the slightly recessed spandrels, the triangular spaces between an arch and its surrounding frame, is a contracted inscription that remains clearly legible: V.D.M:A.I:HLIYVI./HV:H.ET.E.M:M.E:E/.IO. B.MH.O. Nobody has yet produced a satisfactory reading of it. In the 1850s, writers in the Kerry Magazine attempted an interpretation, but their effort amounted to an elaborate romantic fiction spread across several issues rather than a credible decipherment.

The stones almost certainly came from a castle that once stood nearby, probably the structure referred to as the 'House of Hore' in A. O'Daly's satirical poem 'The Tribes of Ireland'. By 1601 the castle was in the hands of the Hussey family. During the Cromwellian campaign, probably in 1649, Walter Hussey garrisoned it, but under pressure from Parliamentary forces the garrison abandoned it and fled to Minard Castle, where they were subsequently killed when it was blown up with gunpowder. The castle at Castlegregory was still standing when the antiquary Charles Smith wrote about it in the mid-eighteenth century, but by 1841, when the Ordnance Survey researchers were compiling their local letters, no trace of it remained above ground. The doorway fragments preserved at Egan's shop are, in that sense, among the very last physical remnants of a building with a violent and documented end.