East Northamptonshire District Council refused permission for the West Coast Energy scheme in January 2011. The energy developer then appealed the decision and a public inquiry was held in November and December last year.
Inspector Paul Griffiths concluded that the benefits of the scheme – which would include four 125-metre high turbines – in terms of the renewable energy it would produce "outweigh the less than substantial harm it would cause to the setting of designated heritage assets".
But the National Trust said the inspector’s decision could have "serious implications for the future of heritage sites" – the proposed Sudborough scheme is near Lyveden New Bield, a National Trust site.
Director-general of the National Trust, Dame Fiona Reynolds, said: "This decision is a landmark case which undermines the protection of our heritage sites. The National Trust sees this development having a substantial impact on the setting of a historic site of the highest designation.
"It provides a clear indication that our cultural heritage is at great risk from inappropriately sited wind turbines and wind farms. If the impacts here are not such to amount to substantial harm on our nation’s heritage it is difficult to conceive where they would be."
But West Coast Energy planning and development manager Jonathan Cawley said that the inquiry process had enabled all of the relevant issues to be debated at length.
He added: "Now that planning permission has been granted we look forward to working with the district council and the local community to deliver the environmental, economic and social benefits of this development at the earliest opportunity."