Plans for a 27-turbine wind farm at Whinash, near Tebay, were rejected because the development would have a detrimental impact on the landscape.
Opponents to Npower Renewables' proposals to build an 18-turbine wind farm at Middlemoor said they have drawn support from the decision.
Dominic Coupe, of campaign group Stop the Alnwick and Berwick Turbines, said: "The Whinash decision is a very important one and it does represent a landmark case.
"We have drawn support from the decision, and our campaign has been boosted, because it is a decision about the beauty of the landscape.
"We have always said the landscape around Middlemoor is sensitive, it is an area of high landscape value and is jammed between the AONB and the national park."
Energy minister Malcolm Wicks and rural affairs minister Jim Knight accepted the recommendations of inspector David Rose to refuse permission for Whinash, following a three-month public inquiry last year.