Scotland's longest and most expensive inquiry

It opened on 6 February, 2007, and ran for 105 days, spread over 11 months, closing on 20 December. During that time it heard from 300 witnesses in Perth, Inverness, Newtonmore and Stirling, heard 17,295 objections and was estimated to cost 10 million.

By the time it ended, two and a half years had passed since Scottish Hydro Electric Transmission, a subsidiary of Scottish & Southern Energy (SSE), and SP Transmission, a subsidiary of ScottishPower, published the proposed route for a 400,000-volt overhead electricity transmission line to replace the existing 132,000-volt line.

Opponents said the inquiry was too long and bureaucratic, failed to involve the public properly and focused solely on the Beauly-Denny plan rather than on any alternative.

Supporters of the 350m, 137-mile line say it is vital for the future of renewables in Scotland, as it will take power from green energy developments in the Highlands and Islands to markets in the south. SSE said putting some of the line underground would increase costs substantially. It was estimated that the cost would rise by 51.3m for a 2.6-mile section of undergrounding, or 90.3m for a 4.9-mile section, increasing the overall cost by 15-26 per cent.

But the plans attracted widespread opposition. Among the objectors were Highland, Stirling, Falkirk, Perth and Kinross and Clackmannanshire councils, as well as the Cairngorms National Park Authority.

The Beauly Denny Landscape Group, which includes the John Muir Trust, National Trust for Scotland and Ramblers Association Scotland, said the upgrade is not required and pylons will harm the environment, including historic sites such as the Sheriffmuir battlefield.

The group also criticised the inquiry for not addressing the need for the upgrade or a possible alternative subsea cable link. Others called the plan an "unnecessary act of vandalism", saying there was no need for it technically or economically.