An environmentalist whose failed legal attempts to block a string of Norfolk road schemes have already added millions of pounds to their price tag has launched a fresh bid to block them.

Climate campaigner Andrew Boswell believes the government has acted unlawfully by allowing the dualling of two sections of the A47 and a major revamp of Thickthorn roundabout.

He believes ministers have failed to fully consider the environmental impact of the projects.

He lost a High Court case last month when Mrs Justice Thornton handed down a judgement dismissing his argument.

However, he is appealing the decision, meaning the case will head to the Appeals Court for one final showdown.

Dereham Times: Mrs Justice ThorntonMrs Justice Thornton (Image: Courts and Tribunals Judiciary)

The case caused several months of delays to the projects and National Highways said this meant the final cost of the works had gone up by tens of millions of pounds, because of construction cost inflation and legal fees.

Chris Griffin, programme leader for National Highways in the east region, said: "We know from speaking to local people there is overwhelming support for these schemes by those that recognise the safety case to improve this very busy road.

"We stand by our plans and remain confident they can deliver significant improvements to both safety and congestion on the A47 as well as a providing a significant boost to the regional economy.”   

Dereham Times: Andrew Boswell is against more road building in NorfolkAndrew Boswell is against more road building in Norfolk (Image: George Thompson, LDRS)

After the case was dismissed by the High Court, former Green city and county councillor Dr Boswell, who uses crowdfunding to raise money for his legal fees, said the judge had made legal errors when deciding the case.

He said: "This case is extremely important as it addresses issues of pressing public importance including how the environmental impacts of new infrastructure are assessed and whether the UK can deliver its climate targets."

Dereham Times: The stretch of the A47 between Blofield and North BurlinghamThe stretch of the A47 between Blofield and North Burlingham (Image: National Highways)

The major schemes include plans to create a new slip road off the A11 northbound at Thickthorn, which will take motorists beneath the A47 before joining traffic on the road heading towards Great Yarmouth - eliminating the need to use the roundabout.

Just over 1.6 miles of the road between Blofield and North Burlingham - considered a crash blackspot by police - are due to be dualled.

And five-and-a-half miles of the road between Easton and North Tuddenham will become a dual carriageway.

READ MORE: Fears Norfolk could miss out on millions for A47 dualling

The projects are intended to reduce congestion, improve safety and create an economic boost for the region.

They were originally announced in 2014, by then prime minister David Cameron, with £300m earmarked for Norfolk schemes, along with other improvements in Cambridgeshire.

Despite the delay caused by the legal challenge, National Highways has said it continues to carry out early works, such as archaeology and utility diversions, on the schemes while it awaits the court’s decision.

Cones could be seen set up in a field off the A47 between Blofield and North Burlingham as workers conducted surveys of the area this month.

It is currently not known what date is set for the case to be heard in the Appeals Court.