An Bord Pleanála yesterday found that Clare County Council contravened its own county development plan on two grounds to grant planning permission for a one-off home near the 17th-century Lemanagh Castle in the Burren.
Earlier this year, the council decided to grant permission for a home near the castle, even though its conservation officer, Risteard Ua Croinin, had warned that the proposal had "the potential to do irreparable damage to the existing monuments and to set an unwelcome precedent for development in the vicinity of Lemanagh Castle and its unique 17th-century house".
An Taisce appealed the decision to An Bord Pleanála, which has overturned the council's decision.
The board found that the council contravened its own plan in relation to the impact the development would have on the archaeological setting of a site of historic importance, and the council's general ban on non-locals building homes in scenic areas.
A spokesman for An Taisce said yesterday: "For a decision to be refused on such a large range of grounds raises major issues of the competence of the council in exercising its functions."
He said: "It also raises the hypocrisy of current Clare County Council policies to promote tourism in the county, while at the same time degrading the setting of one of the county's premier heritage legacies."