The environmental threat on Charles's doorstep

Turnastone Court Farm could come straight out of a John Constable painting. This slice of Herefordshire countryside is populated by breeding curlew, lapwing, redstarts and spotted flycatchers. Cattle and sheep graze its meadows, unploughed for 400 years.

In just over a year's time, however, bulldozers and hard hats will also become part of the scenery. In spring 2007, the National Grid will begin construction on a 115- mile-long gas pipeline straight through the centre of Herefordshire's Golden Valley, in an attempt to come to terms with Britain's growing natural gas needs.

The 48-in diameter steel pipe, intended to transport a fifth of the gas needed to meet rising UK consumption, will run from Felindre, near Swansea, to Tirley, Gloucestershire. It will carry natural gas from two liquefied natural gas terminals in west Wales.

The National Grid says the kilometre-wide corridor it has chosen takes environmental considerations into account, but conservationists are horrified that it will slice through some of England's oldest water meadows and prime agricultural land. Three fields owned by The Prince of Wales's estate are likely to be affected. The Countryside Rest-oration Trust (CRT) is outraged that Turnastone Court is under threat. Robin Page, chairman of the CRT, said that the country's heritage was being squandered and that the National Grid saw the Golden Valley as "easy meat" compared to taking on the Brecon Beacons National Park, the alternative route. "This is one of the last unspoilt areas in the country and it is a nonsense that they will rip up ancient grassland for the sake of imported gas," said Mr Page. "This whole exercise is being driven by the Government which is pressuring the National Grid to get the pipe in as quickly as possible - not in the most environmentally responsible way." The value of the land dates back to Rowland Vaughan, a wealthy Elizabethan landowner who took his social responsibilites seriously. English Heritage lauds his "pioneering work" - the invention of a system of periodically flooding his fields, yielding up to three crops of hay a year.

Daniel Lewis, a project manager at Archenfield Archaeology, who has carried out landscape and building surveyance at Turnastone Court, said the farm's importance lay in its unspoilt nature. "The main value is collective," he said. "It is a worry if the water meadows will be affected as they are a surviving land management feature and show how irrigation was used to produce grass."

The National Grid has written to 430 farmers and landowners informing them that they will send JCBs into a 1km-wide corridor crossing their land in early 2007, pending approval from the Department for Trade and Industry. Some will welcome compensation of about £4,000 per acre - but the news is bad for conservationists, particularly as they were hoping for support from Prince Charles. He now looks set to co-operate with developers.

A spokeswoman for the Prince said it was possible the pipeline would go through three Duchy of Cornwall fields, but that there was nothing he could do once plans had been approved. "Obviously if they are going to build this on Duchy land the Prince would want as little impact on the environment as possible," she said. "The project is in its infancy and I'm sure there are a few hoops they [National Grid] need to jump through yet."

A spokeswoman for National Grid said that the company was in a "positive dialogue" with the CRT to reduce damage. She said contractors would pay attention to the "reinstatement of the landscape to its original condition" after they had finished. "When we put in a pipeline, minimising impact on the environment is extraordinarily important to us, as is the restoration of the landscape," she said.