CAMPAIGNERS fighting plans for a string of pylons across the Suffolk countryside are hoping a key report released today will provide the strongest case yet for burying power lines.

The findings of a crucial independent inquiry into the comparative costs of overground and underground high-power cables, commissioned by the Department for Climate Change in 2010, are due to be published this morning. It is hoped the report will mirror research that led to similar plans for pylons in Lincolnshire being scrapped last week.

The National Grid has previously ruled out an underground route for the 400,000-volt power lines, alongside its existing cables from Bramford, near Ipswich, to Twinstead in north Essex.

It has said that burying cable, which would carry power from Sizewell C and offshore wind farms through some of the most beautiful countryside in the two counties, would cost up to 17 times that of pylons.

But research commissioned by the Irish government found technological advancements have driven down the cost of underground routing. As a result, plans for overhead power lines that would have extended between Grimsby and Boston in Lincolnshire were dropped.

The report also stated that “undergrounding” is the only practical and publicly acceptable way forward for the vast majority of current major projects in Europe.

Tom Leveridge, senior energy campaigner for the Campaign to Protect Rural England, said he hoped the latest report comes to the same conclusion.

He added: “We hope it will finally provide some authoritative and independent information on the real costs of burying power lines. We must not have any decisions to erect ugly pylons in nationally designated landscapes without robust and independent data.”

South Suffolk MP Tim Yeo said if the cost of burying power lines is only three or four times that of pylons, it would be very hard for the National Grid to resist the call for underground cables.

He added: “I hope we get a more transparent assessment of the cost. I’ve been very suspicious for a long time that the cost of ‘undergrounding’ has been greatly exaggerated because National Grid simply don’t want to do it.”

Guy McGregor, Suffolk County Council’s portfolio holder for roads and transport, echoed Mr Yeo’s view.

He added: “We have long argued that the cost of putting cables underground and under the sea is fully justifiable, especially when you consider the awful blight that would be caused by a new generation of pylons being erected across some of Suffolk’s most beautiful landscapes.”

However, councillor David Holland, a member of the campaign group Stour Valley Underground, said he was “very cautious” about predicting the contents of today’s report, explaining that the technical needs of a DC power line in Lincolnshire were different from that of the “less stable” AC line planned for Suffolk.

He said: “In Lincolnshire, National Grid saw that it was not such a big difference between underground and pylons and, combined with the opposition that they had, they decided underground was the way to go.

“But here the capacity is much higher. National Grid want to put a quarter of all the nation’s electricity through these valleys – it is not something that has been seen before and it creates very different problems.”

Mr Holland, of Twinstead, added: “I’m very cautious. We cannot start thinking that the battle has been won.”

Some campaigners have expressed concern that the report was compiled by Parsons Brinckerhoff – a company owned by major National Grid contractor Balfour Beatty. Quality assurance was provided by the Institution of Engineering and Technology.

A spokeswoman for National Grid said the company was looking forward to the publication of the “authoritative and independent study.”

She added: “National Grid has no inherent preference for any single technology.

“We examine each individual project on a case-by-case basis, consulting with communities.

“This new research will provide important evidence to help inform these decisions and we will take into account the report’s findings in our electricity connection projects.”