It is now called the Cumbria Bird Group and I see that they have recently produced an atlas of the breeding birds of the area. http://www.cumbriabirdclub.freeserve.co.uk/breeding_birds_of_cumbria1.htm

I am sure that there will be some info in this book about the past status of the region's eagle population but as information about the breeding sites of these birds in England is rather sensitive - it is best to make personal contact with the local experts for details. You may first have to try and convince them that you are not intending to continue the family tradition of robbing eagle's nests *Smiles*

Good luck and let us know the answers when you find out.