Morag Ellis QC, for the campaigners, said the decision to approve the project was legally flawed and the inspector had "failed to understand" the "historic context" of sites like Lyveden New Bield.
There was concern over the proposed wind farm's impact on local panoramic views, and in particular the setting of the nearby Lyveden New Bield - a National Trust 17th Century lodge which has one of the finest surviving examples of an Elizabethan garden in the country.