The first shots have been fired in a High Court legal battle which could prevent major multi-million pound upgrades to the A47 in Norfolk from going ahead.

The future of the Thickthorn roundabout revamp and dualling of the A47 between Blofield and North Burlingham and Easton to North Tuddenham are the subject of a crucial case at the Royal Courts of Justice in London.

Lawyers representing climate activist Andrew Boswell, who has brought the legal case, told a judge that government decisions to allow those schemes to happen were unlawful.

Eastern Daily Press: How the revamped A47 between Blofield and North Burlingham would look, according to National HighwaysHow the revamped A47 between Blofield and North Burlingham would look, according to National Highways (Image: Highways England)

The ultimate decision of Mrs Justice Thornton could block the schemes from happening or send them back to the drawing board.

And that could have ramifications for road schemes across the county, including the Norwich Western Link.

Eastern Daily Press: Mrs Justice ThorntonMrs Justice Thornton (Image: Courts and Tribunals Judiciary)

But if she rejects Dr Boswell's argument, then National Highways can start work on the long-delayed A47 schemes.

At the High Court in London today (Wednesday, May 10), David Wolfe, KC, acting for former city and county councillor Dr Boswell, said the cumulative carbon impact of all the A47 projects had not been lawfully considered.

He said: "The issue before the court is how transport secretaries, in deciding whether or not to grant a development consent order for each scheme approached the climate change ramifications.

"The point here is how they understood and approached the legality of the exercise that they did."

He told the court the government had a statutory duty to consider the cumulative carbon impact of the schemes and to help meet the government's target to reach net zero by 2050.

Eastern Daily Press: Dr Andrew BoswellDr Andrew Boswell (Image: George Thompson, LDRS)

But he said the secretaries of state had "misdirected" themselves in how they applied the information about what carbon each scheme would produce in terms of construction and traffic and the cumulative impact of that.

That, Dr Wolfe, said was "a legal error", which he argues should render the decisions to grant permission unlawful.

Government lawyers have yet to present evidence, but will argue that the decisions were lawful.

The High Court case will continue for two days.

But a verdict on whether the decisions were lawful or not is likely to be some weeks or months away.

The challenge has meant National Highways - the government company with responsibility for major A roads including the A47 - has not been able to begin construction at the three locations.

Eastern Daily Press: The Thickthorn roundabout revamp is one of the schemes at the heart of the legal caseThe Thickthorn roundabout revamp is one of the schemes at the heart of the legal case (Image: Archant)

The plans for Thickthorn include a new slip road off the A11 northbound, which will take motorists beneath both roads before re-joining traffic on the A47 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 are also due to be dualled.