The Transport Secretary’s decision to approve a controversial project which includes a tunnel near Stonehenge is unlawful because he disagreed with his expert panel with no “proper evidential basis”, the High Court heard.

Save Stonehenge World Heritage Site (SSWHS) is challenging Grant Shapps’ decision to green-light the £1.7 billion development to overhaul eight miles of the A303, including the two-mile tunnel.

The go-ahead was given in November despite advice from Planning Inspectorate officials that it would cause “permanent, irreversible harm” to the Unesco World Heritage Site in Wiltshire.

The three-day hearing before Mr Justice Holgate, which is taking place at the Royal Courts of Justice in London, began on Wednesday.

Grant Shapps
Grant Shapps (Kirsty O’Connor/PA)

In his skeleton argument David Wolfe QC, barrister for the SSWHS group, said: “The Secretary of State disagreed with the assessment of his expert panel, without – unlawfully – there being any proper evidential basis for doing so.

“That happened in part because the Secretary of State misconstrued the advice of Historic England.

“In any event, the Secretary of State’s reasons for disagreeing with the advice of his expert panel were unlawfully inadequate and unintelligible.”

A panel of expert inspectors recommended that development consent should be withheld because the project would substantially and permanently harm the integrity and authenticity of the site, which includes the stone circle and the wider archaeology-rich landscape.

In a report to Mr Shapps, the officials said permanent, irreversible harm, critical to the outstanding universal value of the site, or why it is internationally important, would occur, “affecting not only our own, but future generations”.

SSWHS also argues that Mr Shapps did not properly consider the damage that would be done to a number of prehistoric sites and ancient artefacts and that his approach to the World Heritage Convention was unlawful.

Stonehenge
People view the stones during Summer Solstice at Stonehenge (Ben Birchall/PA)

But in the defendant’s skeleton argument it said that SSWHS’s claim was “unarguable” and should not go ahead.

It added: “In summary the defendant submits that permission should be refused, or alternatively the claim should be dismissed.

“Notwithstanding the labyrinthine complexity of the claimant’s pleadings and skeleton argument, none of the grounds advanced is arguable.

“Stripped to its essentials, the claim simply reflects disagreement with the defendant’s legitimate planning judgment that the scheme should be approved, the defendant having concluded it would cause less than substantial harm to heritage assets in issue (including, in particular, the Stonehenge and Avebury WHS) and that the public benefits of the project outweighed the harm.”

Mr Justice Holgate stressed that the court will not be considering the merits of the project but only whether the Transport Secretary had acted unlawfully.

He added: “We will not be looking at the merits of the project, whether it is a good project or a bad project.

“We are here only, we are concerned only, with the questions of law and whether the Secretary of State has acted unlawfully.”

Campaigners supporting SSWHS’s legal challenge lined up outside the court buildings carrying banners and playing drums alongside a model of Stonehenge.

Senior druid Arthur Uther Pendragon told the PA news agency: “I am here to show druid support for the challenge to the Secretary of State’s stupidity in granting planning permission for what is effectively the wrong tunnel – it’s too short and it’s doing too much damage.

“Not only are the archaeologists against it and the local people against it but the druids are against it.”

John Adams, a director of SSWHS, added: “This is crucial, this might be our last opportunity to stop this road going through the world heritage site.”

The Stonehenge site, together with Avebury, was declared by Unesco to be a World Heritage Site of Outstanding Universal Value in 1986 on account of the size of the megaliths, the sophistication of their concentric plans and the complexes of Neolithic and Bronze Age sites and monuments.

The proposed tunnel is part of a £1.7 billion investment in the A303 between Amesbury and Berwick Down.

The road, which is a popular route for motorists travelling to and from the South West, is often severely congested on the single carriageway stretch near the stones.

Highways England says its plan for a two-mile tunnel will remove the sight and sound of traffic passing the site and cut journey times, but some environmentalists and archaeologists have voiced their opposition to the plan due to its potential impact on the area.

The project is classified as nationally significant, which means a development consent order is needed for it to go ahead.