Consultants were paid £3.8 million by the government to find a location for a lorry park as an alternative to Operation Stack, it has been revealed.

More than 100 potential sites across Kent were subsequently identified - but where they are has never been disclosed.

The search for a site on which several thousand lorries could be held instead of being parked on the M20 was formally abandoned in February - effectively meaning the money spent was wasted.

The government announced it would instead be introducing a solution under Operation Brock involving a moveable barrier along the M20 when there was disruption or delays crossing the channel, caused by bad weather, industrial action or heavy traffic.

The costs of what turned out to be a fruitless search covered an 18-month period, starting in January 2018.

The government had to abandon its initial proposal for a lorry park on land near the village of Stanford, close to the coastbound M20 at Folkestone.

It did so following the threat of court action by campaigners opposed to the scheme.

They had challenged the government about what they claimed was its failure to properly consider the environmental implications.

Then transport minister Chris Grayling backed away and withdrew the plans and then announced that a search would begin for an alternative site.

But despite promising a planning application would come in 2019, nothing was proposed.

The introduction of a contraflow along the M20 in the event of a no-deal Brexit last October appeared to overshadow the quest for a site.

In its response to a Freedom of Information request, Highways England said between January 2018 and March 2020, £3.8m went on consultancy fees.

These were paid to contractors to identify sites and to carry out an initial assessment.

A sum of £1.1m was spent between January 2018 and July 2018; and a further £2.7m was spent between July 2018 and January this year.

"If we release site option information the likelihood exists that estate agents would be unwilling to market properties at unaffected value if they believe a locality could be blighted by the possibility of future development..."

Highways England said in a statement: "We have always been upfront about our work to improve the road network's resilience when there is disruption to services across the English Channel.

"In February the government announced that we would install a new moveable barrier system that can be mobilised quickly to help queue lorries on the M20 while keeping the road open to traffic in both directions."

The search for a potential site began in 2015 when then Chancellor George Osborne allocated £250m to the project.

Details of potential sites were drawn up in a report for Highways England but the locations have not been disclosed.

In its response to our FOI request, officials said it would not be in the public interest to do so - partly because it could affect property prices.

"On balance it was considered that the public interest in maintaining the exemption outweighs the public interest in disclosure as it could prejudice the commercial interests of private property owners," it said.

"If we release site option information the likelihood exists that estate agents would be unwilling to market properties at unaffected value if they believe a locality could be blighted by the possibility of future development."

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