Informal talks offer the best prospect of avoiding a post-Brexit “breakdown” in cross-Channel traffic between the UK and EU amid a prospect the border may be closed.

That is the view of John Keefe, director of public affairs for Getlink UK – formerly Eurotunnel.

Keefe told a European Tour Operators’ Association (ETOA) Brexit seminar in London: “It’s a quarter to midnight in the [Brexit] negotiations and we are finally talking about practical issues.”

But the talks on practicalities are not at the government level. Keefe explained: “We can talk to UK government departments about any issue.

“[But] when we talk to the French government, they say ‘We can’t talk to you’, even though they are party to a bilateral [Channel Tunnel] agreement, because all the negotiations are at the level of the EU.

“Officials say: ‘While negotiations are going on, the EU stands together as a bloc. If you become a third-party country, third-country rules will apply.’ We can’t get into the detail.”

Keefe told the ETOA seminar: “Dover is at the forefront of how our borders will be handled. Traffic goes in both directions, [but] in one direction we may have to apply EU third-country rules.

“We know at the UK border there will be no new controls because the UK government has told us. Nothing will change at the UK border – nothing will change for customs [and] no VAT changes.

“Going the other way there will be immigration controls. You will be required to show your passport. Trucks could be required to go through a variety of processes from having to show documents to having goods tested in a lab.”

He warned: “Worst case, the UK government says the border could be shut. Dover could be closed. Calais could be closed against us.”

Keefe said: “The Channel Tunnel was designed to be free-flowing [and] there are few reasons to stop a vehicle [at present].”

He noted contingency plans drawn up by the UK Department for Transport (DfT) aim at “managing traffic prevented from getting through the border”.

“They will keep traffic on the M20. The coast-bound lanes will become a truck path. London-bound lanes will become a contra-flow with a speed limit of 40mph. “

Keefe warned: “If there is no deal there will be significant disruption to traffic within a very short period of time.”

He noted 9,000 vehicles a day use the tunnel and Dover handles 10,000 a day. “The M20 can hold 2,000 vehicles. If it [parking] is extended to the M26 there is room for another 2,000, then the government would use Manston Airport [in Kent], capacity 7,000.”

The DfT also proposes diverting traffic to other ports. Keefe noted: “There are often only one or two ships a day [at these ports].”

He warned: “The scenario is of a very quick breakdown in the Southeast of England.”

However, Keefe suggested the impasse in talks between the EU and UK at the Strasbourg summit in September proved “a turning point”.

He said: “The no-deal threat became very real. A ripple has gone through Europe. In local regions that benefit from trade or tourism [with Britain] there is a strong desire to keep the UK attached [to Europe].

“There is now a Brexit strategy committee at the French regional level and the French government has appointed a Brexit coordinator.”

Keefe described “a tangible change in attitude” and said: “There has been a seismic shift in the way of working on Brexit. There is no official position on this. [But] there are informal talks on what third-party rules mean.”

He insisted: “The objective is to find the most-frictionless solution possible. It has not been made easy by the negotiations, but we have to take a pragmatic view. The concept of grid-lock is rejected on both sides.”

Keefe added: “We fully intend to keep up our services.”

However, he declined to comment on whether delays can be expected at the end of March and into April next year. He said only: “We will be working at full capacity.”