Wildlife TV presenter Chris Packham and a former government chief scientific advisor are backing an environmental campaigner's legal battle to block the dualling of the A47.

The pair have given their support to Dr Andrew Boswell, ahead of a High Court hearing this week at which he will again try to halt three improvement schemes for one of Norfolk's major roads.

Officials say the projects - to dual the A47 at Blofield and Easton and upgrade the Thickthorn junction with the A11 - are needed to improve safety, cut congestion and encourage economic growth.

But climate activist Dr Andrew Boswell is try to stop them, saying their environmental impact will be too great.

Eastern Daily Press: Dr Andrew Boswell at the Royal Courts of Justice in LondonDr Andrew Boswell at the Royal Courts of Justice in London (Image: Dan Grimmer)

Last year, after a two-day High Court hearing, judge Mrs Justice Thornton dismissed Dr Boswell's argument that the cumulative carbon impact of the A47 schemes had not been properly considered by the Department for Transport, when transport secretaries granted permission.

But Dr Boswell was granted the right to appeal, focussing on the carbon cumulation issue, with Lord Justice Coulson saying: "The judge may well have been right in her conclusion, but I consider that the contrary case making up this single ground has a real prospect of success."

The former Green city and county councillor's legal challenge has caused controversy, with Broadland MP Jerome Mayhew and Norfolk County Council leader Kay Mason Billig among those who have criticised his actions.

Eastern Daily Press: The A47 between Blofield and North BurlinghamThe A47 between Blofield and North Burlingham (Image: Highways England)

National Highways - the government company responsible for the road - said it has meant several months of delays to dualling sections between Blofield and North Burlingham and from Easton to North Tuddenham.

Eastern Daily Press: Thickthorn roundaboutThickthorn roundabout (Image: Mike Page)

They said it has pushed up costs, along with those of a revamp of Thickthorn roundabout on the edge of Norwich, by tens of millions of pounds, because of construction cost inflation and legal fees.

Eastern Daily Press: Chris PackhamChris Packham (Image: PA)

But Dr Boswell's challenge has been backed by former BBC Springwatch presenter Mr Packham and Professor Sir David King, the government's chief scientific advisor from 2000 to 2007.

Eastern Daily Press: Sir David KingSir David King

Former University of East Anglia lecturer Sir David, chairman of the Climate Crisis Advisory Group, said the A47 road schemes "ignored the reality" of climate change and the need to ensure infrastructure projects are "fit for purpose".

Mr Packham said: "Dr Boswell is courageously challenging this unsustainable approach in the Court of Appeal by questioning the routine underestimating of the emissions caused by increasing traffic.

"I salute him and all those challenging government climate policies in the courts."

After the hearing - and the judge's subsequent decision - there are no further legal options for either Dr Boswell or the government to challenge or overturn whatever decision is made.