Suffolk highways chiefs have told the government the case for an A12 bypass is stronger than ever – despite a recent funding setback.

The Department for Transport had been expected to decide on Suffolk’s £133million bid for the four villages bypass this summer, but has deferred until autumn.

In response, Suffolk County Council has written to Transport Secretary Chris Grayling, stressing the project’s importance.

The bypass, which would see the A12 take a new route around Marlesford, Little Glemham, Stratford St Andrew and Farnham, has been an aspiration for more than 20 years.

Villagers have complained about traffic and pollution, which they fear will worsen during the construction of Sizewell C, if it goes ahead.

Suffolk County Council also highlighted economic benefits of the “Suffolk Energy Gateway” in its business case submission to the DfT in December.

Since then, the project’s backers claim developments have made the bypass even more essential.

ScottishPower Renewables is planning to develop a 30 acre substation site near Friston, which is expected to place greater demand on the A12. And EDF Energy’s Sizewell C construction plans are also expected to involve a greater reliance on the road.

Previously, the company had proposed bringing some materials by rail and sea. However visitors to a recent community engagement event said those alternatives looked less likely. EDF said it was consulting and no decisions had been made.

Debbi Tayler, of the Four Villages Bypass campaign, said she remained optimistic despite the funding deferral.

“I think, if anything, all of this has strengthened the case for the bypass,” she added.

Andrew Reid, who represents Stratford St Andrew and Farnham at the county council, also remained upbeat.

“We have written again to Chris Grayling to impress upon him the importance of the four villages bypass, particularly in the context of Sizewell,” he said. “The project is absolutely vital.”

Graham Peck, of the Bypass Action Group, which opposes the project, welcomed the funding delay and said he hoped it meant the bypass would not go ahead

“The likelihood of it happening is reducing,” he said.

“But we are not going to rest on our laurels just because the first round of funding has been rejected.”