Plans for a new version of Operation Stack to avert Brexit gridlock in the county could face a race against time to be ready by next year.

Auditors have warned that “considerable work needs to be done” on the £20m plan designed to keep traffic moving after Britain leaves the EU.

The contingency plan - dubbed Operation Brock - involves a plan to use a contra-flow along a stretch of the M20 should there be disruption at the Port of Dover and Calais port or Eurotunnel.

The contra-flow system has not yet been implemented and has faced criticism from KCC, who said it risked “massive disruption” on a similar scale to Operation Stack.

According to a report by the National Audit Office, the Department for Transport’s proposal is not progressing at the rate it should be to be ready by next March.

It says: “Our detailed examination of the contingency preparations suggests that considerable work still needs to be completed.”

The report warns: “Given the need to be ready by March 2019, the project is required to deliver at pace.

"Highways England has reported that the project has very little room for delay, and that it carries significant risks.

"Although a contract to undertake work was awarded on 11 May 2018 and detailed engineering plans have been drawn up, operational plans to put it into place were still being developed.

"The new solution will need to be ready by March 2019.”

“Our detailed examination of the contingency preparations suggests that considerable work still needs to be completed..." - National Audit Office

However, auditors were told that the Department for Transport had reported “it was confident that the project would be delivered on time” while Highways England reported that it remained on track to complete the project by March 2019.

The proposal is expected to cost the Department for Transport at least £20m, according to the NAO and is cited as one reason why the department’s budget for preparing for Brexit is estimated at £93m.

Dover and Deal MP Charlie Elphicke said: “It’s not surprising the watchdog is concerned. The only thing the Department for Transport has done so far to prepare for leaving the EU is scrap the M20 lorry park. The DfT needs to get out of reverse gear, drive forward plans to dual the A2 and turbocharge their preparations for Brexit.”

A Government spokesperson said: “The NAO concludes that the Department is making a determined effort to ensure the UK transport system is fully prepared for EU Exit and acknowledges that the Department has already achieved a great deal.”

“Our work is part of wider government preparations to ensure the UK can deliver a smooth and orderly Brexit, as we move from our current membership of the EU to our future partnership.”