National Highways chiefs hoped the long running planning saga was over when a High Court judge dismissed a challenge to the scheme by campaigners in February after a development consent order (DCO) was granted by the government last year.

But the Court of Appeal has now decided it will grant a hearing to an appeal against the decision by campaign group Save Stonehenge World Heritage Site.

The three-way European MORE joint venture between Spanish contractor FCC, Italy’s WeBuild and Austria’s BeMo Tunnelling is lined-up as main contractor on the eight-mile stretch of road upgrade.

The FCC-led JV has enlisted Atkins, Jacobs and Spanish designer Sener as the design joint venture.

Costain and Mott MacDonald have been awarded the £60m contract to be the project’s Delivery Assurance Partner to help co-ordinate and oversee construction of the scheme.

National Highways said: “We are hugely disappointed by this decision, which will cause more delays to this scheme as the next stage of the legal process unfolds.

“We still have our Development Consent Order (DCO) in place, so the scheme isn’t cancelled. But this extra legal process will delay the start of our preliminary works and we’ll need to adjust the whole main works programme accordingly.”