National Highways is refusing to say when work will start in earnest on three major Norfolk A47 improvement schemes which have been hit with a string of delays and rising costs.

The organisation has yet to confirm when it will begin the multi-million-pound work, long in limbo because of a legal challenge.

The UK Supreme Court turned down eco-campaigner Dr Andrew Boswell's application to continue his long-running legal challenge against the road schemes last month.

With all legal avenues open to Dr Boswell now exhausted, it opens the door for National Highways to start work to dual the A47 between Blofield and North Burlingham and from Easton to North Tuddenham.

Work to dual the A47 at North Burlingham was left in limbo by the legal challengeWork to dual the A47 at North Burlingham was left in limbo by the legal challenge (Image: Mike Page)

But the agency has yet to reveal when that work - or changes to Thickthorn roundabout on the edge of Norwich - will commence.

Pressed on when announcements would be made, a National Highways spokesperson would only state: "We note the decision of the Supreme Court and will give an update in due course."

Officials at National Highways were forced to pause work on the projects because of Dr Boswell's court battle.

Dr Andrew Boswell lost his legal challengeDr Andrew Boswell lost his legal challenge (Image: Dan Grimmer)

They said Dr Boswell's challenge - which claimed the government unlawfully permitted the schemes because the cumulative environmental impact had not been properly assessed - delayed the projects by months, adding millions to the cost.

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While the case rumbled on, National Highways was restricted to work such as archaeological studies and re-routing utilities, rather than the actual dualling work.

Graham Plant, Norfolk County Council cabinet member for highways, transport and infrastructureGraham Plant, Norfolk County Council cabinet member for highways, transport and infrastructure (Image: Norfolk County Council)

Graham Plant, cabinet member for highways, infrastructure and transport at Norfolk County Council, who previously hit out at the slow pace of progress, was reluctant to criticise National Highways for the lack of a definitive timescale.

He said: "I know they need to get permission for gas utility work on the Blofield to North Burlingham section.

"They will also need to get the materials to Norfolk, which will take time.

"Once we get proper summer weather, I think things will crack on at pace."

Thickthorn roundaboutThickthorn roundabout (Image: Mike Page)