The fight to stop overhead cables being erected across parts of rural Conwy and Denbighshire has reached the High Court.
At a hearing in Llangefni on Monday lawyers locked horns over plans by SPManweb for pylons along an 11-mile route linking two windfarms at Clocaaenog with a substation at Glascoed, near St Asaph.
When the process began four windfarms were proposed but two schemes have since been withdrawn.
The courtroom was full to capacity, the observers being largely supporters of the Pylon the Pressure opposition group. The controversial scheme was approved last July by the Secretary of State for Business, Energy and Industrial Strategy.
The objectors included local residents and landowners as well as councils and politicians, all of whom called for the cables to be laid underground.
The judicial review focused on the impact the 18 pylons and cables would have on Berain, the grade two* Tudor farmhouse at Llannefydd, which was home to Katheryn of Berain. Known as “Mam Cymru” (Mother of Wales), she was a powerful noblewoman and a descendant of Henry VII.
John Mars-Jones, who lives there with his wife, Eirian, is one of the leaders of the Pylon the Pressure campaign and his name was cited in the action.
The argument presented by barrister Peter Dixon, for the objectors, was that insufficient consideration had been given to the impact on the heritage of Berain. Some outbuildings are also listed.
Richard Moules, for the department, disputed the claim and said the extra cost of laying cables underground could not be justified.
It is understood that if the appeal is upheld by the presiding judge, Mr Justice Lewis, the original order will no longer be valid and if SPManweb decide to lay the cables underground the application process must begin again. The hearing concluded on Tuesday but Mr Justice Lewis said he would be reserving his judgment.