Exclusive report by political editor Paul Francis

Kent County Council has been told it must reveal details of all the locations it has considered as possible lorry park sites to deal with Operation Stack.

The KM Group has won an 18-month long battle to force the authority to disclose details of the other sites and how much each option might cost.

An information watchdog has ruled that the council was wrong to withhold the information and has ordered it must be disclosed because of the "considerable environmental impact" and the affect on people living in the area.

KentOnline had sought details of other sites under the Freedom of Act and Environmental Information Regulations.

But KCC said it was not in the public interest to release details of alternative sites, maintaining it was commercially sensitive and disclosure could affect land values.

It also argued the release would create anxiety and uncertainty among those living near the other locations.

In a ruling that comprehensively overturns KCC's case and upholds our appeal, the Information Commissioner's Office (ICO) says a list of alternative sites must now be released in the public interest.

The ruling will also mean that information about the possible planning constraints around the M20 site, originally redacted from documents already provided to the KM Group, will be released.

Forced out into the open: read Paul's political blog here>>>

Anne Jones, assistant commissioner for the ICO, said that "there is a strong public interest in disclosing information which would inform public participation and debate around an issue of which there is clearly considerable public concern and anxiety."

She added: "There is a clear need to look at all the options for alternative ways of managing this situation and further disclosure of information which identifies all of the options being considered would aid the council and public in assessing the options fully."

The ruling also rejected KCC's case that it needed "private thinking space" to be able to consider possible solutions to the problems of Operation Stack.

The commissioner said that argument was not valid because KCC had already identified where it wanted to build the site.

"Although the overall decision as to whether to proceed...has not yet been made, the decision or preferred option of where to site one, has."

The ruling has been welcomed by residents and campaigners opposed to the lorry park plan for some 3,000 vehicles but is a setback for the council.

As recently as December, KCC leader Paul Carter told Folkestone and Hythe MP Michael Howard he would not publish the details of the other locations.

KCC has until next week to release the information. It was asked to comment but has yet to respond.