That a subterranean passage should be formally catalogued alongside ring forts and megalithic tombs hints that this is no simple drainage culvert. Tunnels of this kind on Irish demesnes were typically constructed in the eighteenth or nineteenth century to allow servants, farm workers, or livestock to move across an estate without disrupting the carefully composed landscape visible from the great house. The owner's view of sweeping parkland could thus remain uninterrupted by the practical traffic of estate life.

Garbally itself was the seat of the Trench family, the Earls of Clancarty, and the demesne was laid out in the manner of an improving landlord's ambition during the Georgian and early Victorian periods. The house and grounds passed in the twentieth century to the Catholic Diocese of Clonfert, and the estate is today the campus of Garbally College, a secondary school. The tunnel sits within this layered history, a piece of designed landscape infrastructure from one era now embedded in the grounds of an institution with an entirely different purpose.

Because the formal record for this site has not yet been made publicly available, specific details about the tunnel's dimensions, construction materials, or precise location within the demesne remain unconfirmed. What can be said is that the demesne grounds themselves are associated with the school, and access would be subject to the usual considerations around a working educational campus.