The case concerned land off Old Lane, Ightham, near Sevenoaks, which has been home to a gypsy family for more than a decade.
Planning permission was granted by Tonbridge and Malling Borough Council in 2008 for two caravans on the site for occupation by two named individuals and their dependents.
That permission was limited to a period of three years. However, a further consent granted in 2015 extended that to seven years.
Conditions attached to the 2015 permission required that residential use of the site cease on expiry of the seven-year period and that the land be restored to nature.
In November last year, however, Tonbridge and Malling Council granted a fresh consent.
The 2019 permission was again limited to named individuals and dependants living with them, but the number of caravans permitted was increased to three and, crucially, it was not subject to any limit of time.
Amongst other grounds of challenge to the permission put forward by objector, John Miles, was that the council had been influenced by an immaterial consideration.
He argued that the council wrongly took into account that a refusal of permission was likely to lead to an appeal to a planning inspector. If the council lost such an appeal, it would be exposed to a costs order being made against it and, potentially, reputational damage.
Ruling on the case, Judge Neil Cameron QC noted that it was undisputed that the risk of an award of costs or reputational harm are not material planning considerations and allowing such factors to influence a planning judgment would be "illegitimate."
But he added: "It is clear...that there is nothing wrong with officers giving members advice that, in the event of an appeal being made against a decision to refuse to grant planning permission, there is a risk that an award of costs would be made against the council."
It was "entirely appropriate" for planning officers to advise councillors of the potential cost implications of refusing permission, and the judge ruled: "The advice given on costs was not part of the planning analysis or exercise of planning judgment.
"As a matter of fact, the risk of an adverse costs award and the reputational risk were not taken into account as material considerations in the planning analysis or in the exercise of planning judgment."
Miles also put forward numerous other grounds of challenge, alleging that councillors had been misled by officers' reports and had misinterpreted and misapplied national and local planning policies concerning green belt protection and traveller sites.
In rejecting his detailed criticisms of officers' reports, however, Judge Cameron found that they were not misleading when read as a whole and properly informed councillors of planning considerations relevant to their decision.
R on the Application of Miles v Tonbridge and Malling Borough Council. Case Number: CO/4989/2019