A year-long delay in dualling the A428 between Caxton Gibbet and the A1 is “not acceptable”, James Palmer, the mayor of Cambridgeshire and Peterborough, has said.

Mayor Palmer has told Highways England and the Department for Transport that he was not prepared to accept any slippage on the key road upgrade.

The multi-million pound scheme was scheduled to start in 2020 but Mayor Palmer was told about a potential delay until 2021 at a stakeholder conference for the Oxford to Cambridge Expressway.

He said: "The A428 between the Black Cat and Caxton Gibbet is a source of great frustration for many Cambridgeshire residents. There is a daily cost in time and money for people and businesses along this single carriageway stretch of road and the case for dualling is incontrovertible.

"Unlike other key roads in Cambridgeshire and Peterborough, such at the A10, the A428 is the responsibility of Highways England. However, as Mayor I'm keen to put as much pressure on as possible to ensure that work on dualling starts by 2020."

Mayor Palmer said: "I was originally told that construction would start on dualling the A428/Black Cat to Caxton Gibbet in 2020. However, I was informed at the conference that it may have slipped back to 2021. I made clear to senior figures from the Department for Transport and Highways England that this is not acceptable.

"I will be meeting with the Chief Executive of Highways England in July and will keep the pressure up to ensure that construction on dualling starts as soon as possible."

The stretch of the A428 between Caxton Gibbet and the A1 is single carriageway with roundabouts and crossings and routinely suffers congestion during peak periods, causing disruption over a wide area because there are no diversionary routes.

Huntingdon MP Jonathan Djanogly said that 18 months ago Highways England consulted on proposals to provide a dual carriageway on the A428 and responses raised concerns about how the scheme would fit in with a strategic study on improvements to the A1.

He said: "This will require further analysis to fully understand the implications for the A428 scheme. This means that the preferred route announcement has not been possible in 2017 as originally envisaged.

"I have repeatedly raised concerns with Highways England and transport ministers on this and they recognise that the delay is frustrating. However it is important that the scheme meets the long term needs of local communities and road users throughout the region. I shall continue to push on this."