An alliance of environmental and rural pressure groups have said the sums show the proposed 70m turbine will generate less energy than previously predicted but Glyndebourne Opera House has said it will provide enough electricity to almost entirely power the estate.

The South Downs Environmental Protection Consortium South Downs Society includes the Ramblers Society, the Campaign for National Parks, and the Sussex Campaign to Protect Rural England, all of whom have called on the owners of the world-famous Opera House not to go ahead with the wind turbine.

The same organisations have always contested the 850km turbine which was rubberstamped by the Government last July following a public enquiry in February.

Further criticism has been heaped on the plan because the turbine will be based at Mill Plain, near the opera house, which is now part of the upcoming South Downs National Park.