The power company Statera originally dismissed the Saltholme site because it was so environmentally sensitive. When it was arguing for planning permission for a power station nearby at Norton. In section 3.24 of the Norton planning application below it said: 
“The substation at Saltholme is adjacent to the Cowpen Marshes SSSI…and as an important migratory bird habitat the location is not ideal.”

Or use the viewer below:

16_1978_ful-planning__design_and_access_statement-1997802norton-thorpethewles

Link: https://www.developmentmanagement.stockton.gov.uk/online-applications/applicationDetails.do?activeTab=documents&keyVal=OB11M1PKIP300