Exclusive report by political editor Paul FrancisFull story here.
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.
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.
ICO Decision Notice FER219834 Kent County Council here.