Frustrated Norfolk leaders have questioned whether the Acle Straight dualling will ever happen - with fresh concerns raised over tiny snails which play a key role in whether work can be done.

Dykes around the road are one of the few habitats of the Little Whirlpool Ramshorn Snail - which are on an international 'red list' of endangered species.

Because the miniscule molluscs are so rare they are protected by law, so National Highways has to ensure any work does not threaten them further.

Efforts have been made to relocate the snails away from the A47 to another part of the marshes - with the success of the move crucial if the road is ever to be dualled.

A five-year study into whether those relocated snails are thriving began in 2018.

It was discussed at a recent meeting of the A47 Alliance, made up of business leaders, politicians and council officers from Norfolk, Cambridgeshire, Lincolnshire and Suffolk.

National Highways officers said results had been "mixed" and described the relocation as a "significant challenge".

That frustrated campaigners who have pressed for the Acle Straight dualling.

Nova Fairbank, chief executive of Norfolk Chambers of Commerce, said: "You've been doing various relocations of snails for the 12 years I've been in Norfolk and I'm still waiting."

And Colleen Walker, Labour county councillor for Great Yarmouth's Magdalen division, said: "We cannot go on like this. The loss of life on that road is outrageous. While I know we have to look after the environment, it is people first in my book."

Speaking after the meeting Alan Kirkdale, programme development manager for National Highways, said: "It is too early to say how successful this has been until we have collated and discussed the findings with our partners on this project.

“As with all our schemes there is a balance to be struck between the need to improve road infrastructure and protect the natural environment; we are part way down the road with this work."

Some £300m of work is earmarked for the A47, including changes to the Thickthorn junction and dualling from Blofield to North Burlingham and Easton to North Tuddenham.

But the dualling of the Acle Straight has yet to be included in any of the government's long-term plans.