The site at Adas Farm, Hardwick Lane, Lyne, Chertsey, was mainly woodland, with a grassy clearing, when the group of Gypsies arrived in May 2017.
According to the High Court judgement, a total of 23 households, comprising 86 adults and children, many of them related, moved onto 13 caravan pitches on the 3.7-acre green belt site.
Runnymed Borough Council obtained a High Court injunction within days of the group's arrival and the site was vacated.
But the judge said the "unathorised development has remained ever since."
The council issued an enforcement notice, requiring the site's restoration, in June 2017, but that had yet to be complied with, the court heard.
One member of the group, Nino Lee, sought retrospective planning permission to change the site's use to that of a residential caravan site.
But the council refused and, following a public inquiry, a planning inspector rejected Lee's appeal in May last year.
The inspector said the encampment was "inappropriate development" which was "by definition harmful to the green belt".
But he acknowledged that there is "significant unmet demand" for authorised Gypsy sites in the council's area.
And he noted the "pressing needs" of some members of the group, particularly children, some of whom suffer from "severe conditions".
But he ruled that refusing planning permission was a "proportionate and necessary" interference with the group's human right to respect for their family lives.
The fact that it was "an intentional unauthorised development" also weighed in the balance against the group.
After another member of the group, Hughie Sykes, challenged the inspector's ruling in court, the housing secretary accepted that the decision should be quashed and the group's planning appeal reconsidered.
According to the High Court judgment, the housing secretary "conceded that the inspector failed to provide adequate reasons to address the question whether suitable permanent sites might become available in neighbouring areas by the end of a period of temporary planning permission".
The council, however, stuck to its guns and successfully defended the inspector's decision.
Sykes argued that, whilst the inspector was entitled to refuse permanent planning consent, he should have granted a temporary permission enabling the group to live on the site for at least four years.
That, his lawyers submitted, would have given time for alternative, authorised, sites to be provided - either in the borough or elsewhere in Surrey - on which the group could lawfully settle.
Dismissing Sykes' complaints, however, Mrs Justice Lang said the inspector had given "adequate and intelligible reasons" for refusing to grant temporary planning consent.
He had rightly "grasped the nettle" and was not obliged to assume that the council would overcome the shortfall in authorised Gypsy sites in its area within a four-year period.
The inspector, the judge said, gave "careful and conscientious consideration to the personal circumstances of the members of the group, both on an individual basis and collectively".
And he was entitled to conclude that time-limiting the planning permission would not reduce the overall harm to the green belt to a level where it would be clearly outweighed by the considerations in the group's favour.
In December, the High Court extended an injunction on a Gypsy encampment in an area of woodland in Surrey, ruling that the camp was a "substantial and unlawful development in open countryside".
A Planning article examining how injunctions banning unauthorised Gypsy and traveller sites are impacting on provision can be read here.